Remote and Hybrid Working during Crisis: Challenges and Implications for Employee Development in Africa

*Deseré Kokt and Crispen Chipunza*

#### **Abstract**

The emergence of the COVID-19 pandemic in 2020 and the associated lockdowns imposed by governments exposed disparities in how organisations on different continents were prepared for unplanned uncertainties. While the global north organisations, with their advanced adoption of 4IR technologies, quickly moved in to find affordable ways to ensure business continuity, adjustments by organisations in the global south were challenged by lack of modern advanced affordable technologies. The abrupt adoption of technologies associated with the fourth industrial revolution [4IR] in the global south meant an increased emphasis on remote working - a concept that has been taboo, especially in South Africa. The adoption meant fitting into a new world of work, which requires agility, re-learning, and de-learning of skills. The chapter aims to unpack the work challenges organisations face in times of crises and what it means for employee development in an African context.

**Keywords:** remote working, hybrid working, fourth industrial revolution [4IR], Africa, new world of work, employee development

#### **1. Introduction**

The new world of work, which has evolved mainly due to globalisation, the internet and the evolution of 4IR technologies, has generated an altered reality for both organisations and employees. Broad trends that have emerged in the new world of work include increased virtualisation and digitalisation, more part-time employment [or gig work], people working from home or any other location and employees being more frequently connected to their jobs than ever before [1]. The advent of the COVID-19 pandemic and the subsequent lockdown of economies have brought about increased remote and hybrid working. Current realities in the new world of work will subsequently be unpacked, as well as the concepts of remote and hybrid working followed by the need for continuous employee development in the African context. The chapter is informed by a literature review and desktop search of the current realities that inform the complexity of remote and hybrid working in an African context.

#### **2. Current realities in the new world of work**

In the 1980s telecommuting became a way of helping employees manage and balance work and family responsibilities. Over the years, telecommuting grew as technology advanced and economic systems evolved as a result. With the advent of COVID-19 global remote working became the new universal 'norm'. Prior to Covid-19 remote working was not a common practice, especially in the African context. Reports on South Africa indicate that 21% of professionals worked from home before the pandemic. The number increased to 79% during the pandemic [2].

The Gartner poll indicates the likelihood of more employees working remotely either full-time and/or part-time. According to Lavelle [3], 74% of CEOs interviewed planned on shifting at least 5% of employees to remote working. Amazon also announced its intention to create 3 000 work-from-home positions in South Africa [4]. Amazon is experiencing a boom due to increased online shopping, which has led to the creation of work-from-home jobs on a global scale. This shows that companies are contemplating remote working to a greater extent than before the COVID-19 outbreak.

The Gartner poll surveyed 145 CFOs and senior financial managers during April 2020 and found that most (51% of respondents) were expecting up to 30% decline in revenue. The respondents also showed caution in contemplating longterm investments. The findings further indicate that 55% of organisations intend to redesign roles, supply chains and workflows and that geographic diversification and investment in secondary markets were envisioned to mitigate and manage risk in times of disruption. These developments imply that a more complex business environment is likely to evolve, which can impact the operational models of organisations [5].

Results of the Gartner poll further indicate that 32% of companies were contemplating the replacement of full-time workers with contingency workers [6]. This places more emphasis on the prevalence of gig workers, which is already a trend in the new world of work. Gig employment, something that has not really existed in the African context is likely to become more prolific. This implies more part-time work as opposed to fix-term employment. The notion of gig work and/or part-time work is a contentious issue in the South African context where workers and especially unions push for full-time and fixed employment contracts.

Working remotely requires integrated and customised information technology (IT) systems to enable companies to not only enable remote working but also to track the work employees are performing. In this sense, the Gartner poll also showed that companies are increasingly using technologies to assist them - 16% of employers indicated that they have increased the use of technology to track work, computer usage and the emails and internal communication of employees.

This notion is supporting the central role of IT in organisations – which is likely to become more pronounced given that organisations require customised IT systems to run their operations [7]. Also, the IT and engineering professions are propelling the new world of work. Engineers are devising technologies on various platforms, e.g. nanotechnology, building rockers and spaceships for galactic travel (notably Virgin Galactic and SpaceX), autonomous vehicles (e.g. Tesla) including the planned Mars expedition of 2022 spearheaded by the tech entrepreneur, Elon Musk [8, 9]. These engineering advances need IT professionals to programme the systems. In fact, the programming of smart and integrated systems drives innovation on a global scale (e.g., Amazon) and programming is a key skill.

*Remote and Hybrid Working during Crisis: Challenges and Implications for Employee… DOI: http://dx.doi.org/10.5772/intechopen.107023*

Remote work has implications for managers. Apart from the people skills required from managers, they need to be flexible and have the necessary soft skills to motivate and support staff. Managers also need to have digital skills to comprehend the systems involved in remotely managing and supporting staff. Employees also demand increased transparency—this was already apparent prior to COVID-19 [5]. In fact, the ways in which managers and organisations treated employees during COVID-19 can have implications for the employer of a choice strategy of organisations and ultimately talent management.

According to the research of Bersin [10] deep layoffs, especially in times of crises, have dire consequences for the future sustainability of organisations. This is mainly due to the loss of critical skills. A loss of critical skills impacts negatively on customer and stakeholder relationships, thus affecting the future viability of organisations. In addition to this, employees that were not retrenched go through a 'survivor syndrome' where they contemplate whether they will be next. This creates a less than conducive work environment where employees experience psychological stress that can have a significant impact on their engagement, motivation and commitment. It is thus pertinent that leaders show they care for their employees. Digital transformation driven by the various 4IR technologies is the future and organisations do not have any other option but to adapt to its demands, thus necessitating leaders and managers that are able to act as change agents spearheading this new reality.

#### **3. Remote and hybrid working**

Remote working can be characterised by working in a highly flexible environment where telecommuting, teleworking, virtual work, distributed work or distance work is the norm [11]. Remote working involves flexible work arrangements that allow employees to work from home or any other locality but not the central office. With this arrangement, employees do not have physical contact with their colleagues except for an online connection. Hybrid working is when employers expect workers to commute to the workplace during specified times – thus incorporating remote working and at times being office-based.

Remote working is not something new and has existed for decades, especially in the United States of America [USA], where around 3.9 million employees were working from home before the outbreak of COVID-19 [12]. An engineer Jack Nilles is believed to have coined and introduced the term 'telecommuting' in the 1970s. This was necessitated by the oil crisis that hits the USA in the 1970s and the idea that employees could work remotely to continue with production [13].

#### **3.1 Challenges of remote and hybrid working**

Remote and hybrid working can be an exciting prospect for employees who seek flexibility, but it can also result in psychological well-being challenges for others. Research by Russell [14] indicates that remote working has the potential to result in 'no work boundaries' that might ultimately lead to increased job stress, depression, anxiety, loneliness and isolation mainly caused by a deprivation of social contact [15–17].

Remote working can, however, benefit employers as the best talent can be sourced in an international sphere. Working hours are flexible and employees have greater autonomy and less office interruptions [18]. Pertinent challenges related to remote

working involve the likelihood of higher costs due to having a home office, employees that lack digital skills may find the work challenging, and team spirit may suffer as there are limited network opportunities that may cause psychological health to suffer as a result.

Compared to traditional employment, modern employees are expected to work in technological advanced environments. This means the nature of jobs changed from using predominantly manual approaches to performing jobs that are more mentally and emotionally demanding [19]. These realities are likely to have significant implications for organisations. The post-COVID-19 world is likely to generate more gig work, as well as more employees working from home. Gig work is based on skills and individuals that work from home need to have the proper systems in place to perform their jobs, notably internet connectivity, laptops, etc. Gig work is likely to exacerbate already existing inequalities, especially in the South African and African context.

Further challenges include managing one's own schedule and time, blurred lines between personal and professional life, distractions, reduced supervision and direction, social isolation, working in pyjamas and lack of motivation and long-term vision. This will be discussed below.

According to Al-Habaibeh, Watkins, Waried and Javareshk [20] *managing one's own schedule and time* is one of the many challenges faced by employees working from home. Remote workers have the freedom to manage their own time meaning they need to take responsibility for performing their jobs. The concept of 'normal business hours' remains a global business practice for most organisations as it relates to efficient time management. Specified work hours create personal and work boundaries for employees, which separates work from personal interests. Furthermore, without proper time management and scheduling, many employees are likely to relax more and work less hours as expected by the employer. Employees might procrastinate and postpone work to 'later'. This can create work and personal conflict. Therefore, employees should try to have time structures in place for each day of the week working from home [21].

Gibbs, Mengel and Siemroth [22] note that *blurred line between personal and professional life* is a challenge as *t*here is no geographic division between work and personal space. Ideally, home is a place where employees relax, feel safe and have security. As far as remote work is concerned, employees can easily forget the work and not meet work deadlines. Furthermore, Janza [23] mentions that some remote workers have indicated that they are never 'off the job'. This means they feel a compulsion to always check emails or get 'just one last thing done'. In other words, some remote workers might not find it easy to knock off and relax whilst others might continue working.

Another challenge identified by Nyberg et al. [24] is *distractions.* Employees can have a schedule or workspace but being productive during work hours can be a challenge due to unplanned or unwanted distractions. Home surroundings such as television, favourite books, laundry, dishes, child responsibilities and many more can easily become distractions. Noise cancelling headphones can help avoid auditory distraction and should therefore be considered. It is important that employees create and maintain a firm barrier between work and home life. Family members should respect working time at home as they would respect working time at the office.

*Reduced supervision and direction* is a challenge for some remote employees identified by Toniolo-Barrios and Pitt [25]. Many employees at the office complain about the supervision and direction from their managers but managers serve a crucial role in directing employees on what should be done including timeframes, supervising tasks and daily job responsibilities. Direction and supervision are important so that

#### *Remote and Hybrid Working during Crisis: Challenges and Implications for Employee… DOI: http://dx.doi.org/10.5772/intechopen.107023*

managers can provide effective feedback to employees on their progress and job execution. Employees working from home receive less supervision and direction, which can influence job performance. Parker et al. [26] mentions that 29% of managers question whether employees have the required knowledge to do their jobs from home while 27% noted their employees lacked essential skills to properly execute their jobs from home. Male managers were also found to be warier than female managers. Fifteen per cent (15%) of female managers indicated that they lacked confidence in their remote employees whereas 36% of male managers had little trust in their remote employees' skills [26].

Toniolo-Barrios and Pitt [25] further state that *social isolation* is a challenge that cannot be ignored. Humans are social beings that need to interact with others. However, working from home takes away the social aspect of the workday and this might result in loneliness and/or psychological frustrations. Technology, such as Zoom, can make remote work more interactive but it cannot replace face-to-face interactions. W*orking in pyjamas* is a challenge that many remote workers take for granted. Working in pyjamas is easy for most employees because they do not have to wake up early and dress for the office. A study conducted by Adam and Galinsky [27] in the Journal of Experimental Social Psychology found that people perform job tasks better when wearing clothes with 'symbolic meaning'. For example, doctors perform better at their jobs while wearing lab coats. Thus, working in pyjamas is not recommended for any employee because pyjamas and sleep are strongly connected in most people's minds. Moreover, bathing and feeling clean improves most people's professionalism and performance.

Davis [21] reckons that *lack of motivation and long-term vision* can also be a challenge to the remote workers. Being surrounded by the career-driven energy of ambitious and passionate colleagues around the office rubs off and can inspire colleagues to be more productive and motivated. However, working from home eliminates this energy and some employees might become lazy, unmotivated, and thus underperform.

#### **3.2 Challenges of remote and hybrid working in Africa**

The development of Africa, which has always lagged makes it difficult for hybrid or remote working. Remote working requires technological resources that are efficient, yet, for example, many African countries have complexities in terms of power and subsequent internet connectivity [28]. Electricity in Africa is not constant. Half the time it is not available, and this eventually affects the notion of effective remote working and productivity. The provision of other alternatives to electricity, such as generators, power banks and solar-powered devices is often regarded as an add-on to the already struggling companies compared to government-provided electricity, which seems to be cheaper. In addition, many African countries rely on the western world for technological development. As such their financial muscle to establish and adopt advanced technology for remote or hybrid working is often hampered. In South Africa, for example, a study by [29] revelated that several organisations were caught off guard by the pandemic as they had to adjust budgets and ensure employees had access to laptops and other aids. In addition to this, many employees lacked the requisite technological skills to ensure effective working from home. This lack of technological skills made organisations working in the African context have concerns about risks to security systems and privacy rights as employees worked remotely.

According to Osoba [30], many large parts of Africa still do not have wide coverage of networks at the same time the existing connectivity access is riddled with low bandwidth. This is exacerbated by the socio-economic environment in the African context, where workers do not own homes in urban areas but in rural areas. During the last two years (2020 to 2022) where COVID -19 was a menace in the whole world, remote working has seen many African workers drifting to rural places to save costs, yet, in those rural places, there are added challenges including poor location, affecting network connectivity. This has made it difficult for organisations to even fathom hybrid node of work or manage employee and in some cases team performance.

The African way of living is such that families live together in a household. Remote working for an African worker means disruption of family-set up and dealing with challenges one does not often confront when they are at the workplace. The set-up of many African homes where never meant to accommodate someone working from home - hence, during a crisis like Covid-19, very few African workers were fortunate enough to make temporary arrangements. Those who could shift to home set-up meant unavoidable distractions by children or other cohabiters [31].

In Africa, with remote working comes along the fear of employees working long hours and claiming to be compensated for overtime, the legal as well as health and safety issues. Chetty [32] reports that organisations in Africa have often failed to attract top talent because of their reluctance to adopt remote or hybrid working as a result of poor technological advancement and strict legal issues. However, the risk is failing in competitiveness, productivity levels and investment losses. Africa still has a long way to go when it comes to hybrid or remote working as it must grapple with the inherent infrastructural inequalities compared to the global north countries. In addition, inequalities experienced by workers, especially women and workers in lowincome employment mean the need to have strategies that will enable the employers to embrace digitisation that will recognise inequalities among employees and allow working from anywhere.

#### **3.3 Support strategies for remote and hybrid workers**

It is important that employers offer support to their employees especially when they are working from home. The impact of remote working will vary from person to person due to differing needs. Generally, employees require safety, security, stability, trust relationships and social cohesion as well as the need to experience purpose and meaning in their jobs [33]. Management should support employees with flexible policies and procedures as well as provide work-related and personal support to employees. An integral part of this is to emphasise psychological wellness for both employees and managers [33]

Evanoff, Strickland, Dale, Hayibor, Page, Duncan, Kannampallil and Gray [34] in their study revealed that perceived low support from a supervisor predicts a range of negative psychological consequences, including anxiety and depression. Therefore, employers can develop managers' skills, offer progression, set clear expectations, and offer choice to employees.

These techniques will be discussed below:

• Develop manager's skills: line managers must be suitably skilled for remote working to be beneficial for employees. Managers need to develop skills to manage remote workers through easy communication, monitoring and motivating them as effectively as they would if they were at the office [35].

*Remote and Hybrid Working during Crisis: Challenges and Implications for Employee… DOI: http://dx.doi.org/10.5772/intechopen.107023*

#### **3.4 Advancing the psychological well-being of remote and hybrid employees**

Employee well-being should be a priority and promoted within the organisation because it is not only beneficial for employees for even for the organisation itself. Employee well-being incorporates all aspects of well-being, it is about optimising both physical and psychological health [38]. Aldana [39] recons a healthy and happy workforce is more productive and engaged and that work life has a big impact on general employee happiness.

Feeling painful emotions disappoints or failure is a normal part of life and being able to manage these emotions is essential for long-term well-being. Psychological well-being is, however, compromised when negative emotions are extreme and interfere with a person's ability to function in his/her daily life. Effective psychological functioning involves the development of one's potential, having some control over one's life, having a sense of purpose and experiencing positive relationships [38, 40].

García-Moya, Brooks, Morgan and Moreno [41] suggest that psychological wellbeing can be promoted through positive experiences. Employee well-being can be promoted by focusing on the following issues: senior leaders' participation, raising awareness of psychological well-being, promoting employee dialogue and decision making, developing a culture of openness, inspiring work-life balance, learning and development, positive working relationships and social activities and peer support and buddy systems. These measures will be discussed below.

involved and well informed about new developments within the organisation, they are likely to experience increased motivation. Furthermore, leaders should include employees in decision-making processes, not only regarding their jobs but in the organisation's vision and direction as well [36]. Additionally, management should manage organisational changes such as implementing new systems in a collaborative and inclusive way [38].

*Remote and Hybrid Working during Crisis: Challenges and Implications for Employee… DOI: http://dx.doi.org/10.5772/intechopen.107023*

#### **4. Employee development for remote working in Africa**

With barriers to digital adoption and inequalities in employment and infrastructure, African employees need to be continuously kept abreast as the world enters a new era of high-tech, remote and hybrid working. With a high population of youth unemployed, Africa's growth will depend on the employment of these youths provided they have a great degree of digital technology skills. For example, Sub-Saharan Africa is estimated to require digital skill knowledge by 2030, presenting an opportunity of around \$130 billion for investors and education providers to train the future workforce and those already in the employment space [45]. The COVID-19 pandemic has taught Africa that there is a need to shift the frontier of skills that are essential for the future world of work, which is influenced by technology and automation. From an African perspective, this means disrupting the cultural barriers to working by emphasising the urgent need for digital and socio-behavioural skills for employees to enable them to effectively work from anywhere.

The rurality of Africa with its richness in natural resources is suitable for the development of socio-behavioural skills and digital skills of its human capital, thereby disrupting the traditional notion of firms and expanding global supply chain by allowing rural clusters of firms to emerge, grounded on traditional cultures fused with digital technologies for global relevance purposes. In tandem with the notion above, studies [1, 46] have pointed out that many new skills for the future are those that would require agility in terms of how employees work and adapt to new ways, as opposed to what employees know. Employers in Africa, therefore, need to keep pace with technology, and see the re-learning of new skills, thinking and behaviours of employees as a transformative vehicle for remote and hybrid working going into the future world of work. The anticipated envisaged continuous transformative development of employees to enhance remote and hybrid working in Africa in the future world of work cannot be achieved when the continent does not deal with the issues of power supply and internet access [47].

#### **5. HR implications for remote and in working in Africa**

With an existence of work that is uncertain as crises come one after the other, digital technology continues to be the vehicle that will ripple away the traditional ways of working and embrace remote or hybrid working. This new wave of change presents an opportunity for human resource practitioners to elevate themselves from just being operational to strategic through being proactive and demonstrating what they can offer in this digital era. For example, during crises situations, the role of HR in seeing significant training and upskilling of employees is imperative. The future world of work emphasises critical skills versus roles [48]. While this might be the case, in the African context, specifically, this emphasis cannot be done in isolation but must be complemented by good, improved electricity and internet connection availability in remote rural areas and townships as well as taking into consideration the gradual adoption of technology in workplaces of the continent. The African concept of 'ubuntu' – 'am because we are' must not be seen to be dehumanised because of remote working.

Linked to this, the 'ubuntu' concept is for HR leaders to determine how productive and efficient employees can be given a history of strong unionism and fighting the employer as a solidarity group (physically present) and not from isolated remote working environments. In addition to this, most workers in Africa, especially in countries like South Africa are known for deriving their power in their numbers flexible working is a new concept developing in Africa, HR leaders need to also consider how it affects the mental health of employees. The implications are that resilience coaching to curtail the much-anticipated added strain to employee engagement, culture and value propositions should be prioritised. This means activities such as onboarding will be remotely done, but the question then is, how HR leaders will embark on such activities remotely, to ensure that there is bonding among team members to make new recruit's part of the organisational culture virtually.

### **6. Conclusion**

The chapter unpacked the COVID-19 challenges in the African context, specifically those pertaining to remote and hybrid working. Support strategies were proposed to advance the psychological well-being of employees as well as to assist employee development in the African context.

One of the top priorities for HR departments posts any crisis is to establish a balanced structure to foster a thriving workplace culture that is suited to flexible working conditions. The challenge for HR leaders is to maintain the social dynamics between employees within an increasingly dispersed workforce.

### **Author details**

Deseré Kokt\* and Crispen Chipunza Central University of Technology, Bloemfontein, Free State, South Africa

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Remote and Hybrid Working during Crisis: Challenges and Implications for Employee… DOI: http://dx.doi.org/10.5772/intechopen.107023*

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[39] Aldana S. 7 Important reasons to offer employee well-being at work. 2022. [Internet]. 2022. Available from: https:// www.wellsteps.com/blog/2020/01/02/ employee-well-being-at-work/

[40] Huppert FA. Psychological Wellbeing: Evidence Regarding its Causes and Consequences. Applied Psychology. Health and Well-Being. 2009;**1**(2):137- 164. DOI: 10.1111/j.1758-0854. 2009.01008

[41] García-Moya I, Brooks F, Morgan A, Moreno C. Subjective well-being in adolescence and teacher connectedness: A health asset analysis. Health Education Journal. 2015;**74**(6):641-654

[42] Bartels AL, Peterson SJ, Reina CS. Understanding well-being at work: Development and validation of the eudaimonic workplace well-being scale. PLoS ONE. 2019;**14**(4):e021

[43] Panaccio A, Vandenberghe C. Perceived organizational support, organizational commitment and

psychological well-being: A longitudinal study. Journal of Vocational Behavior. 2009;**75**(2):224-236

[44] Banerjee K. Why Companies Are Adding Mental Health Benefits for Their Employees. 2021

[45] International Finance Corporation [IFC]. Digital Skills in Sub-Saharan Africa [internet] 2018. Available from: https://www.ifc.org/wps/wcm/connect/ 58f4396b-fcee-49c8-82a4-614fd3d53ea3/ Digital+Skills+Report\_WEB\_ ES.pdf?MOD=AJPERES&CVID= mGkda3h%20

[46] The World Bank. The Future of Work in Africa: The Roles of Skills, Informality, and Social Protection in Unleashing the Promise of Digital Technologies for All [internet] 2019. Available from: https:// www.worldbank.org/en/region/afr/ publication/africa-future-of-work

[47] Monthe P. 3 ways Africa needs to adapt to the era of remote working [Internet] 2022. Available from: https:// www.weforum.org/agenda/2022/03/3 ways-africa-remote-working/

[48] Reed J. South Africa: Could Employers Who Don't Offer Remote Working Lose Valuable Talent? [Internet] 2022. Available from: https:// www.mondaq.com/southafrica/ health-safety/1171244/couldemployers-who-don39t-offer-remoteworking-lose-valuable-talent

#### **Chapter 6**


*4.4. Results*

As mentioned above, each model was evaluated with 20% of data for cross validation. The SVM presented a general accuracy of 68.51 % which was the model with the lowest performance in cross-validation. Its behavior is compared with that of the rest of the analyzed classes in Figure 9. Therefore, the use of this model in the multisensory helmet has been discarded.

**Figure 9.** Cross-validation results with 20% for the SVM.

An average accuracy of 78.26% has been achieved by NB in all the classes, as shown in Figure 10. Its performance has been better in class 5 and class 11. Despite having a better result than SVM it has been discarded since there were models that had better performance.

**Figure 10.** Cross-validation results with 20% for the NB.

Figures 11 and 12 show the performance of static NN and CNN respectively. In Figure 8 it can be observed that there is not a significant difference in the performance of NB, which had an accuracy of 78.56%. On the contrary, CNN, which allows for the implicit extraction of characteristics and for maintaining the relationships between the information regarding the dataset, had a considerably better result, with an accuracy of 92.05%. Our innovation comes on the proposed implementation of a CNN in a safety helmet as a proposal to reduce accidents and fractures in work areas, also through the use of technologies such as IoT for rapid synchronization of alarms that are sent to supervisors to take immediate action.

**Figure 12.** Cross-validation results with 20% for the CNN.

Given the above, CNN is the model that has been implemented in conjunction with the ThingsBoard platform. ThingsBoard and CNN work independently, creting an alarm system in a simulated environment that can serve as an higher security approach to a work environment. CNN is in charge of validating the information obtained from the platform, see Figure 13.

Previously it was mentioned that the creation of the deep models was through the "trial and error" approach, but the possible problem of overfiting should not be left aside, that is why Table 12 shows the results for the CNN in 10-Folds that shows the average performance from an objective point of view of the models.

**Figure 13.** System of alarm rules established in ThingsBoard.

In the next section, the conclusions drawn from the conducted research are described, and the contributions of this work to the state of the art are highlighted.

### **5. Conclusions and Discussion**

Our work has a history of electronic development in which the use of a multisensory helmet was established. Through a conditional model of input–output rules, we tried to detect the different situations to which a worker was subjected. However, the input–output techniques presented false positives and false negatives with 60% accuracy in the best of cases, which is why after several stages, it was decided to implement AI in the helmet. The 60% that was described a moment ago is due to the combination of different circumstances, that is to say, the correlation that exists on the independent characteristics, is for that reason, that through techniques that find linear and nonlinear relations we decided to innovate in the present work. Since it is necessary to find the patterns that determine a particular action, for them there are the techniques of deep learning as our work presents

The comparison between different models of AI has been made in this research. Our innovation comes from the moment of using a CNN that in the literature has been used to analyze images or videos in intelligent helmets with the aim of saving lives. However, we proposed a multisensory approach to real-time feature analysis. Through the transmission of data through specialized IoT devices, a smart helmet has been designed to monitor the conditions in a working environment. The application areas of this proposal are industrial and agricultural sectors and any other sector that involves risk for the workers. Thanks to the helmet, different injuries can be avoided, and in case an accident occurs the damage caused to the worker is lessened through prompt attention or detection.

It is possible to observe in Figures 9–11 that the MSA presented many false positives on majority classes in sample size, and even false positives of repeated classes (class 6) on more than five different classifications. NB and NN had a better performance in minority classes, however, there are three different classifications in false positives in classes such as 11, 9, 7, 2, 1 and 0. The NN has a strong resolution where the classes mentioned above still present false positives but with a decrease to 2 wrong classes in almost all cases.


**1. Introduction**

For more than a century, chlorination has been the most common method used worldwide for drinking water disinfection. Chlorine and chlorine-based compounds are widely used for the control of waterborne pathogens because of their high oxidizing potential, low cost, and

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

residual disinfectant properties that prevent microbial recontamination. Unfortunately, the chemical reaction between chlorine and organic compounds in water generates carcinogenic agents such as trihalomethanes and halogenic acetic acids [1, 2]. Furthermore, some resistant microorganisms may only be inactivated with very high chlorine doses, which can exacerbate the formation of disinfection by-products (DBPs) [3]. Presently, growing concerns about the potential hazards associated with DBPs have boosted efforts to develop chlorination alternatives. Ozonation is effective at inhibiting a variety of pathogens; however, its disadvantages include the high cost and the potential formation of DBPs such as bromate in seawater [4, 5]. Other water treatment methods such as ultraviolet (UV) radiation, ultrasound, cavitation, or heat application can be used for the inactivation of organisms. Although these methods do not produce DBPs or other problematic chemical residues, they require substantial energy consumption and have high operational costs [5]. Besides, the efficiency of UV disinfection is greatly dependent on water quality because the activity of UV light is substantially decreased by turbidity or organic matter present in water [5].

mechanism is still unknown for this process. Pressure cycling is defined as a repetitive pro-

*Escherichia coli* Inactivation Using Pressurized Carbon Dioxide as an Innovative Method for Water Disinfection

suggests that the decompression process may lead to mechanically induced explosive cell

membranes [11–13]. In previous works, the pressure cycling procedure has been conducted

decompression and compression [8, 10, 13, 15]. Despite the good bactericidal performance of

(<1.0 MPa) will enhance the bactericidal activity. Therefore, in this study, we examined the

tion applications such as ballast water treatment. Comparisons of *E. coli* inactivation caused

ined for various conditions of pressure, temperature, flow rates, and working volume ratios (WVRs). In particular, the influence of pressure cycling on *E. coli* inactivation was evaluated.

tron microscopy (SEM). The research objective was to evaluate the bactericidal effectiveness

ambient temperatures, and consequently, high-pressure (4–50 MPa) or ultra-high-pressure (200–700 MPa) conditions are vital for sufficient inactivation. However, to be more attractive

at lower pressures. In this study, we employed the use of a liquid-film-forming apparatus, which enabled improvements in the interaction efficiency but with lower pressures (<1 MPa)

The experimental apparatus for disinfection was a stainless steel chamber with an internal volume of 10 L and pressure tolerance up to 1.0 MPa. The device was designed with a solid stream nozzle and shield to enable vigorous agitation of the influent in such a way that produced liquid films along with fine bubbles (**Figures 1**–**3**). The device was supplemented

high speed through a small nozzle and directed onto the shield. The highly pressurized fluid stream thus collided with the bubble-generating shield. Subsequently, numerous gas bubbles,

pressure prior to the treatments. Sample water was then pumped into the device at

**2. Novel idea: apparatus for forming highly dissolved gas in water**

release requirements are drawbacks owing to the costly and complex operating proce-

technology enhanced by pressure cycling [11–13, 15], the high pressure and

and pressurized air were evaluated in both natural seawater and arti-

for disinfecting water, with the goal of addressing the abovementioned

methods in the field of food preservation, the interaction efficiency

and pathogens in the foodstuffs is probably limited at low pressures and

ruptures [14], while the compression process may intensify the mass transfer of CO2

dures. Presently, it is not clear whether pressure cycling with low-pressure CO2

between each cycle of raised/lowered pressure.

[9, 10]. Evidence so far

discharges between each cycle of

http://dx.doi.org/10.5772/intechopen.68310

at low pressures and with no

against *E. coli* was exam-

at less than 1.0 MPa for seawater disinfec-

treatment were assessed by scanning elec-

technology needs to be implemented

across cell

209

treatments

cedure that involves the decompression and compression of CO2

with high-pressure operations (8–550 MPa) and with CO2

effect of pressure cycling on the bactericidal performance of CO2

ficial seawater. The inactivation performance of pressurized CO2

emerging problems associated with water disinfection technology.

This study investigated the use of pressurized CO2

Changes in cell morphology after pressurized CO2

in terms of its economic feasibility, pressurized CO2

for the water disinfection purposes.

pressurized CO2

release of CO2

by pressurized CO2

of pressurized CO2

For pressurized CO2

between CO2

with CO2

CO2

Sterilization by using pressurized CO2 has been an active research field for decades [6, 7]. CO2 has been used extensively to sterilize dried food and liquid products via a nonthermal sterilization method [8] because of its effectiveness in inactivating microbes, nontoxicity, and low cost [9]. Prior research on high-pressure CO2 treatments has investigated the effects of several factors such as pressure, temperature, type of microorganisms, agitation speed, decompression rate, and pressure cycling on the inactivation capacity of this method [6, 8, 10–15]. Most studies have reported that high-pressure operating conditions (4–50 MPa) are required to inactivate significant numbers of pathogens [7, 9]. Subsequently, certain concerns involving high-pressure operations (i.e., the need for heavy-duty pressure equipment, high initial investment costs, energy consumption concerns, and pressure control and management issues) have hampered the implementation of high pressurized CO2 preservation technology at a large scale within the food industry.

In recent years, pressurized CO2 has shown great potential as a sustainable disinfection technology in water and wastewater treatment applications [16–22] largely because this method does not generate DBPs [9, 22]. Kobayashi et al. [16, 17] employed CO2 microbubbles in the treatment of drinking water and succeeded in inhibiting *Escherichia coli* within 13.3 min. However, the pressure (10 MPa) and temperature (35–55°C) requirements for effective inactivation [16, 17] are still high from a practical standpoint. Our research group has developed a novel method that uses low-pressure CO2 treatments (0.2–1.0 MPa) based on technology that produces high amounts of dissolved gas in water to inactive bacteria and bacteriophages in freshwater [19–21] and seawater [23, 24]. Cheng et al. [19] suggested that the sudden discharge and resulting reduction of pressure could cause cells to rupture via a mechanical mechanism, and further, that this would be lethal to cells at high levels of dissolved CO2 at 0.3–0.6 MPa and room temperature. Vo et al. [20, 21] demonstrated that acidified water and cellular lipid extraction caused by pressurized CO2 at 0.7 MPa and room temperature were major factors for efficient disinfection within a treatment time of 25 min.

Previous research has shown that pressure cycling is a potential means to improve bacterial inactivation during pressurized CO2 treatments [8–10, 13, 15]; nevertheless, the inactivation mechanism is still unknown for this process. Pressure cycling is defined as a repetitive procedure that involves the decompression and compression of CO2 [9, 10]. Evidence so far suggests that the decompression process may lead to mechanically induced explosive cell ruptures [14], while the compression process may intensify the mass transfer of CO2 across cell membranes [11–13]. In previous works, the pressure cycling procedure has been conducted with high-pressure operations (8–550 MPa) and with CO2 discharges between each cycle of decompression and compression [8, 10, 13, 15]. Despite the good bactericidal performance of pressurized CO2 technology enhanced by pressure cycling [11–13, 15], the high pressure and CO2 release requirements are drawbacks owing to the costly and complex operating procedures. Presently, it is not clear whether pressure cycling with low-pressure CO2 treatments (<1.0 MPa) will enhance the bactericidal activity. Therefore, in this study, we examined the effect of pressure cycling on the bactericidal performance of CO2 at low pressures and with no release of CO2 between each cycle of raised/lowered pressure.

residual disinfectant properties that prevent microbial recontamination. Unfortunately, the chemical reaction between chlorine and organic compounds in water generates carcinogenic agents such as trihalomethanes and halogenic acetic acids [1, 2]. Furthermore, some resistant microorganisms may only be inactivated with very high chlorine doses, which can exacerbate the formation of disinfection by-products (DBPs) [3]. Presently, growing concerns about the potential hazards associated with DBPs have boosted efforts to develop chlorination alternatives. Ozonation is effective at inhibiting a variety of pathogens; however, its disadvantages include the high cost and the potential formation of DBPs such as bromate in seawater [4, 5]. Other water treatment methods such as ultraviolet (UV) radiation, ultrasound, cavitation, or heat application can be used for the inactivation of organisms. Although these methods do not produce DBPs or other problematic chemical residues, they require substantial energy consumption and have high operational costs [5]. Besides, the efficiency of UV disinfection is greatly dependent on water quality because the activity of UV light is substantially decreased

208 *Escherichia coli* Escherichia coli - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications

 has been used extensively to sterilize dried food and liquid products via a nonthermal sterilization method [8] because of its effectiveness in inactivating microbes, nontoxicity,

of several factors such as pressure, temperature, type of microorganisms, agitation speed, decompression rate, and pressure cycling on the inactivation capacity of this method [6, 8, 10–15]. Most studies have reported that high-pressure operating conditions (4–50 MPa) are required to inactivate significant numbers of pathogens [7, 9]. Subsequently, certain concerns involving high-pressure operations (i.e., the need for heavy-duty pressure equipment, high initial investment costs, energy consumption concerns, and pressure control and manage-

nology in water and wastewater treatment applications [16–22] largely because this method

treatment of drinking water and succeeded in inhibiting *Escherichia coli* within 13.3 min. However, the pressure (10 MPa) and temperature (35–55°C) requirements for effective inactivation [16, 17] are still high from a practical standpoint. Our research group has developed a

produces high amounts of dissolved gas in water to inactive bacteria and bacteriophages in freshwater [19–21] and seawater [23, 24]. Cheng et al. [19] suggested that the sudden discharge and resulting reduction of pressure could cause cells to rupture via a mechanical mechanism,

and room temperature. Vo et al. [20, 21] demonstrated that acidified water and cellular lipid

Previous research has shown that pressure cycling is a potential means to improve bacterial

ment issues) have hampered the implementation of high pressurized CO2

does not generate DBPs [9, 22]. Kobayashi et al. [16, 17] employed CO2

and further, that this would be lethal to cells at high levels of dissolved CO2

has been an active research field for decades [6, 7].

has shown great potential as a sustainable disinfection tech-

treatments (0.2–1.0 MPa) based on technology that

at 0.7 MPa and room temperature were major factors

treatments [8–10, 13, 15]; nevertheless, the inactivation

treatments has investigated the effects

preservation tech-

microbubbles in the

at 0.3–0.6 MPa

by turbidity or organic matter present in water [5].

and low cost [9]. Prior research on high-pressure CO2

nology at a large scale within the food industry.

novel method that uses low-pressure CO2

extraction caused by pressurized CO2

inactivation during pressurized CO2

for efficient disinfection within a treatment time of 25 min.

In recent years, pressurized CO2

Sterilization by using pressurized CO2

CO2

This study investigated the use of pressurized CO2 at less than 1.0 MPa for seawater disinfection applications such as ballast water treatment. Comparisons of *E. coli* inactivation caused by pressurized CO2 and pressurized air were evaluated in both natural seawater and artificial seawater. The inactivation performance of pressurized CO2 against *E. coli* was examined for various conditions of pressure, temperature, flow rates, and working volume ratios (WVRs). In particular, the influence of pressure cycling on *E. coli* inactivation was evaluated. Changes in cell morphology after pressurized CO2 treatment were assessed by scanning electron microscopy (SEM). The research objective was to evaluate the bactericidal effectiveness of pressurized CO2 for disinfecting water, with the goal of addressing the abovementioned emerging problems associated with water disinfection technology.


5.1. Basic requirements of coordinator

4. to confirm whether necessary inspections have been given to the donors and recipients

Composition: Includes the brain death or DCD identification of neurological and surgical

Composition: Includes professional transplantation medical staff and related staff.

1. receive DCD-related information and DCD authentication written information;

4. being responsible for the acquisition, preservation and transshipment of organs.

Department, logistics department, coordinators and Red Cross staff, and so on.

2. coordinate with the relevant departments and arrange the cremation;

tion of the cemetery and the memory activities;

4. cooperate with the Red Cross in publicity; and 5. deal with other left-over issues after DCD work.

3. assess the recipient indications, contraindications, general condition and timing of

Composition: Formed by the Medical Department, the vehicle team, the Propaganda

3. communicate and coordinate with relevant departments and arrange the implementa-

DCD work in Hunan Province has always been in a leading position in the country. The success of DCD work in Hunan Province is mainly attributed to the strong support and cooperation of the Provincial Health and Family Planning Commission, the Red Cross Society and the transplant hospitals. Figure 1 shows DCD in eight hospitals in Hunan Province for 2010–2016 and Figure 2 shows implementation of DCD in China. The work of organ transplantation in China is also known as the "Hospital president project" and all the transplant centers that have better development are fully supported by their presi-

1. experts in determination group at least are associated experts and

2. experts must undergo a specific brain death and DCD training.

to ensure clinical efficacy.

120 Organ Donation and Transplantation - Current Status and Future Challenges

4. DCD determination group

experts. Requirements:

5. OPO procurement group

surgery; and

6. DCD post-processing group

1. body maintenance;

Responsibilities:

dents [29].

2. evaluation of donor quality;

Responsibilities:

"There is no organ transplant without organ donation, no organ donation without coordinator" [30]. This fully demonstrates the importance of coordinators in organ donation and transplantation. At present, there are two main types of coordinators in China: Red Cross Coordinator and OPO Coordinator.

Based on relevant regulations "Management of human organ donation coordinator" promulgated on June 1, 2013, the coordinator shall meet the following conditions [31]:

According to the "Regulation on Procurement and Distribution of Human Donated Organs (Provisional)" issued by the National Health and Family Planning Commission, the OPO coordinator should meet one of the following conditions:

In addition, the coordinator should also have a serious working attitude, a certain degree of communication skills and language skills as well as good psychological quality and psychological endurance. Only in this way can we properly handle the relationship with donors and their families, do a good job in organ donation coordination and push forward the donation of human organs [32].

#### 5.2. Coordinator training in China at the current stage

From 2010 to 2012, the Chinese Red Cross is mainly responsible for the training of coordinators. After the establishment of China Organs Donation Administration Center after 2013, it specially undertook the training of coordinators and organized 4–5 training courses each year. It invited experts in medicine, law, ethics and psychology from all over the country to give lectures and organized domestic relevant experts who compiled the "Training Materials on Human Organ Donation Coordinator in China" (the first and second volumes) [33]. The coordinators were required to attend relevant studies and pass the qualification examination. At present, a management system of coordinators with rigorous management, impartial examination and scientific training has been formed, which has delivered a large number of high-quality coordinators for the DCD work in China and, at this stage, and has made great contributions to the successful development and promotion of DCD work in China.

5.  DCD organ transplant ethics form

13. organ procurement record form

18. donor medical death certificate

20. organ donation process record form

Figure 8. Flow chart of organ transplant file management system [33].

19. cremation certificate

12. donor management form

15. the HLA matching report 16. the recipient information

6. potential organ donor's family informed consent

8. brain death determination family's informed consent

10. the donor electroencephalogram inspection report

14. the donor discharge diagnosis/patient history information

17. recording video or photo material throughout the process of organ donation

However, there are also some problems. For example, the standard norms are not uniform, and the paper materials are not conducive to long-term preservation; inspection and data statistics are inefficient. Through continuous discussion and exploration and the cooperation of various field experts, we have made use of information technology and Internet technology to develop an organ transplant file management system that is suitable for China. The

Current Situation of Organ Donation in China http://dx.doi.org/10.5772/intechopen.74711 123

7. brain death determination family member's application form

#### 5.3. Organ donation coordinator working procedures in current China


*3.8. Statistical Analysis*

Discriminant analysis was performed using IBM SPSS Statistics 22 (ver. <IP_ADDRESS>) (SPSS Inc., Chicago, IL, USA) and the MetaboAnalyst 4.0 software (McGill University, Montreal, QC, Canada) for a comprehensive and integrative data analysis.


*3.2. Nutrient Intake and Body Weight Change*

Table 2 presents the intake of DM, OM, CP, NDF, and ADF, weight gain, and BW change in growing goats fed TMR containing untreated and treated discarded durian peel with additives. DM, OM, CP, and NDF intake were not different among treatments except ADF. ADF intake was different (*p* < 0.05) between FDP and FDPLM, which contained 0.24 g/d and 0.20 g/d, respectively. Weight gain and BW change in goats were not affected (*p* > 0.05) by dietary treatments.

**Table 2.** Effects of untreated and treated discarded durian peel in TMR on intake and body weight change in growing goats.

SEM = standard error of the mean; BW0.75 = metabolic body weight; DM = dry matter, OM = organic matter; CP = crude protein; NDF = neutral detergent fiber; ADF = acid detergent fiber; BW = body weight. a,b Means in the same row with different letters differ (*p* < 0.05).


4.3.2. Two-Period DID

The regression coefficients in the baseline regression may be overestimated due to sequential correlation issues. To solve this problem, we will adopt a two-period estimation strategy according to Bertrand et al. (2004) [29]. The data will be divided into two periods based on the point in time of the policy. That is, the variables in the two periods are averaged to construct a two-period DID sample.

The estimation result is shown in column (2) of Table 4. We find that the coefficient on Treat\*Post is significantly negative at the 1% level, suggesting that the city cluster policy can reduce city carbon emissions even after considering potential serial correlation issues.


**3. Mathematical model**

inside the nozzle depends strongly on its density, which in turn depends on the temperature and, in the high velocity, compressible regime, on the velocity itself. As inside the nozzle the radial temperature profile is very sharp, small variations of its shape, for instance its peak width, lead to appreciable changes in the radial mass distribution that reflect directly on the velocity. All this is more clearly seen and quantified using simple 1-D, two zone models in which only axial dependence is considered of an inner hot zone and an outer cold region. By assuming sonic flow at the nozzle exit, these simple 1-D models are able to predict quite reasonably the measured temperatures (within the experimental uncertainty), but give very

The purpose of this work is to present a validation of the most frequently used plasma cutting torch models employing not only temperature but also velocity values as the experimental data to be confronted with. In order to do this, a 2-D model (similar to those proposed in the literature) was developed and applied to the same 30 A oxygen cutting torch that was used in a previous velocity measurement experiment. In this paper the plasma torch, model assump‐ tions, governing equations, boundary conditions and the physical details of the model are presented. The calculated distributions of temperature and velocity and its comparison with

The high energy density cutting torch used in this numerical study consisted of a cathode centered above an orifice in a converging-straight copper nozzle. The cathode was made of copper (7 mm in diameter) with a hafnium tip (1.5 mm in diameter) inserted at the cathode center. A flow of oxygen gas cooled the cathode and the nozzle and was also employed as the plasma gas. The gas passed through a swirl ring to provide arc stability. The nozzle consisted in a converging-straight bore (with a converging length of 1 mm, and a bore 1 mm in diameter, 4.5 mm length) in a copper holder surrounding the cathode (with a separation of 0.5 mm between the holder and the cathode surface). To avoid plasma contamination by metal vapors from the anode (usually the work piece to be cut), a rotating steel disk with 200 mm in diameter and 15 mm thickness was used as the anode (Freton et al., 2002). In this study, the disk upper surface was located at 6 mm from the nozzle exit. The arc was transferred to the edge of the disk, and the rotating frequency of the disk was equal to 24 Hz. At this velocity, a wellstabilized arc column was obtained, and the lateral surface of the anode disc was completely not melted. Thus, practically no metal vapors from the anode were present in the arc. A scheme

By performing a small orifice (1 mm in diameter) on the lateral of the cathode surface the pressure in the plenum chamber (*pch*) was measured by connecting a pressure meter at the upper head of the cathode. The gas mass flow (*dm/dt*) injected in the torch was also registered. In this experiment, the arc current, the plenum pressure and the gas mass flow, were fixed to

of the torch indicating several geometric dimensions is presented in Fig. 1.

values of 30 A for the arc current, *pch* = 0.7 MPa and *dm/dt* = 0.71 g s-1, respectively.

imprecise values (100% off) of the flow velocity (Kelly et al., 2004).

the experimental data are shown.

68 Computational and Numerical Simulations

**2. Arc cutting torch**

### **3.1. Computational domain**

The schematic of the modelled domain for the simulation is presented in Fig. 2. AC is the cathode part, including a 0.75 mm radius hafnium insert (AB). DE represents the copper nozzle. The edge of the domain EF is located at a radius of 10 *RN* (Gonzalez-Aguilar at al., 1999). FG represents the anode located at 6 mm from the nozzle exit. A mass flow rate of 0.71 g s-1 with a vortex injection that leads to a ratio of the azimuthal to the axial inlet velocity of tan (13º) ≈ 0.23 was used at the torch inlet CD.

**Figure 2.** Cutting torch computational domain.

### **3.2. Model assumptions**

The most frequently used cutting torch models use the LTE approximation, with the plasma flow in chemical equilibrium, and the internal energy of the fluid being characterized by a single temperature *T*. Other assumptions are:

**a.** The plasma flow is two-dimensional and axisymmetric. There are two effects that could break these assumptions. The first one is catastrophic: the double-arcing phenomenon in which a secondary arc appears from the cathode to anode passing across the nozzle (Prevosto et al., 2009c). The second one is a non-symmetric alignment of the torch. Both effects are not considered in this work.

Momentum conservation

Internal energy conservation

r

¶

r

¶

r

emission coefficient (NEC) (Naghizadeh-Kashani, et al., 2002).

and azimuthal –*uz*– components), *p* the pressure, *δ*¯

The first is the current continuity equation

and the second is one of Maxwell's equations

t

 m

permeability of free space.

In (3) the stress tensor is given by

where

( ) ( ) 0.

( ) ( ) 4 0,

where *ρ* represents the total mass density, *u*¯ the fluid velocity (having, axial –*ux*–, radial –*uy*–

current density, *B*¯ the magnetic field (only the azimuthal component was considered), *e* the internal energy, *q*¯ the total heat flux, *E*¯ the electric field and *εN* the plasma radiation net

Two further equations are required to describe the electromagnetic part of the plasma model.

 Governing equations**

The fluid part of the thermal plasma model can be expressed as a set of general transport equations expressed in conservative form as a balance among accumulation, net flux and production, namely:

$$\frac{\partial \mathcal{\partial} \boldsymbol{\nu}}{\partial t} + \nabla \cdot \overline{\boldsymbol{f}\_{\boldsymbol{\nu}}} - S\_{\boldsymbol{\nu}} = \mathbf{0},\tag{1}$$

where Ψ is a conservative quantity, *t* represents time, *f* ¯ *ψ* is the total (i.e., convective plus diffusive) flux of Ψ, and *S*Ψ is the net production rate of Ψ. The set of conservation equations describing such a flow can be expressed as follows.

Total mass conservation

$$\frac{\partial \lrcorner \rho}{\partial t} + \nabla \cdot (\rho \,\overline{u}) = 0. \tag{2}$$

Momentum conservation

**a.** The plasma flow is two-dimensional and axisymmetric. There are two effects that could break these assumptions. The first one is catastrophic: the double-arcing phenomenon in which a secondary arc appears from the cathode to anode passing across the nozzle (Prevosto et al., 2009c). The second one is a non-symmetric alignment of the torch. Both

**b.** At atmospheric pressure or above, the plasma is generally collision dominated: the mean free path for all species is much smaller than the macroscopic characteristic lengths. Therefore, the continuum assumption is valid; and the plasma is considered as a Newto‐

**c.** The plasma gas is assumed to be pure oxygen in LTE with negligible concentration of metals in the plasma. The infiltration of metal atoms into the plasma can be due to the evaporation of copper and hafnium from the cathode and the nozzle. Atoms from the work-piece could also be diffused into the plasma, but generally in a negligible concen‐

**d.** Non turbulent fluctuations are considered in the electromagnetic parameters, which results in a considerable simplification to the problem. So, for the calculations of the

**h.** The anode was considered as a porous free boundary characterized by its electrostatic

The fluid part of the thermal plasma model can be expressed as a set of general transport equations expressed in conservative form as a balance among accumulation, net flux and

diffusive) flux of Ψ, and *S*Ψ is the net production rate of Ψ. The set of conservation equations

( ) 0.

r

¶ + Ñ× =

y y

 + Ñ× - = ¶ *f S*

0,

¯

*t* (1)

¶ *u t* (2)

*ψ* is the total (i.e., convective plus

electromagnetic parameters the mean plasma state parameters are considered.

effects are not considered in this work.

70 Computational and Numerical Simulations

potential.

production, namely:

Total mass conservation

**3.3. Governing equations**

nian fluid following Navier-Stokes equation.

tration considering the high mass flux rate of the working gas.

**e.** The electrodes sheath phenomena are not included in the modelling.

**g.** In the energy equation the viscous dissipation term is considered negligible.

**f.** Hall currents and gravitational effects are considered negligible.

¶y

> r

where Ψ is a conservative quantity, *t* represents time, *f*

describing such a flow can be expressed as follows.

$$
\frac{
\partial \left(
\rho \,\overline{u}
\right)
}{
\partial t
} + \nabla \cdot \left(
\rho \,\overline{u} \otimes \overline{u} + p \,\overline{\overline{\delta}} - \overline{\overline{\tau}} \right) - \overline{J} \times \overline{B} = 0.
\tag{3}
$$

Internal energy conservation

$$\frac{\partial(\rho e)}{\partial t} + \nabla \cdot \left(\rho \overline{u} \, e + \overline{q}\right) - \overline{J} \cdot \overline{E} + p \nabla \cdot \overline{u} + 4\pi \, \varepsilon\_N \frac{p}{p\_{ATM}} = 0,\tag{4}$$

where *ρ* represents the total mass density, *u*¯ the fluid velocity (having, axial –*ux*–, radial –*uy*– and azimuthal –*uz*– components), *p* the pressure, *δ*¯ ¯ the identity tensor, *τ*¯ ¯ the stress tensor, *J* ¯ the current density, *B*¯ the magnetic field (only the azimuthal component was considered), *e* the internal energy, *q*¯ the total heat flux, *E*¯ the electric field and *εN* the plasma radiation net emission coefficient (NEC) (Naghizadeh-Kashani, et al., 2002).

Two further equations are required to describe the electromagnetic part of the plasma model. The first is the current continuity equation

$$
\nabla \cdot \overline{J} = 0,\tag{5}
$$

where

$$
\overline{J} = -\sigma \nabla \phi,\tag{6}
$$

and the second is one of Maxwell's equations

$$
\nabla \times \overline{B} = \mu\_0 \,\overline{J},
\tag{7}
$$

where *σ* is the electric conductivity, *ϕ* is the electrostatic potential and *μ*0 the magnetic permeability of free space.

In (3) the stress tensor is given by

$$
\pi\_{i,j} = \mu\_e \left( \frac{\partial \boldsymbol{u}\_i}{\partial \boldsymbol{\alpha}\_j} + \frac{\partial \boldsymbol{u}\_j}{\partial \boldsymbol{\alpha}\_i} - \frac{2}{3} \boldsymbol{\delta}\_{i,j} \frac{\partial \boldsymbol{u}\_l}{\partial \boldsymbol{\alpha}\_l} \right), \tag{8}
$$

where *μe* is the effective viscosity and the 2/3 factor in the fluid dilatation term, ∂ *ul* / ∂ *xl* , comes from the Stokes hypothesis for the dilatation viscosity. The total heat flux in (4) describes the heat transported by conduction and the enthalpy transport by mass diffusion, and is defined as

$$
\overline{q} \equiv -\kappa\_{\mathfrak{e}} \nabla T + \overline{\Gamma}\_{\mathfrak{e}} h\_{\mathfrak{e}},\tag{9}
$$

**3.5. Turbulent model**

The closure of the system equations requires extra relationships (which are commonly known as the turbulence model) to calculate the turbulent enhanced viscosity and thermal conduc‐ tivity. There are in the literature turbulence models of varying degrees of sophistication: the Reynolds stress model (RSM), the *k*- ε model and its variants, the renormalization group (RNG) *k*-ε model, the RNG *k*- ε model taking into account the low Reynolds number effect, the realizable *k*- ε model and the Prandtl mixing length model (Zhou et al., 2009). The two most

Following previous published models (Freton et al. 2002; Freton et al., 2003), the Prandtl mixing

where *c* is an adjustable parameter and λ is a local thermal radius which characterizes the boundary of the high velocity arc core, defined as the radial distance from the axis to the point at 2000 K (Yan et al., 1999). As inside the nozzle the radial temperature profile is very sharp (Prevosto et al., 2009c), λ results very close to the nozzle radius *RN*. It has been found that for transferred arcs the turbulent Prandtl number can be approximated by unity (Fang et al., 1994).

thus only the parameter *c* in (13) needs to be adjusted by comparing the numerical results with the experiment. The turbulent viscosity for isotropic turbulence was calculated taking into

> . æ ö æ ö ¶ æ ö ¶ æ ö = ç + ÷ ç ÷ ç ÷ ç ÷ ç ¶ ¶ ÷ è ø è ø è ø è ø *x z t m u u l y*

*y yy*

Table 1 summarizes the prescribed values of the physical quantities (or its spatial derivatives) on the boundaries shown in Fig. 2. In addition, the voltage drop between the cathode AC and the anode FG was adjusted in order that the integrated value of the axial current density on a given section corresponds to the value of the electric current of the torch. An external source term to increase the temperature was applied at the axis of the torch AG to initiate the current. A current value of 30 A was used in this study, in according to the value used in the experi‐ ments. Also, at the hafnium insert AB the maximum value of the axial current density on the

1/ 2 2 2

, *ml c* (13)

Numerical Modelling of a Cutting Arc Torch http://dx.doi.org/10.5772/57045 73

º1, *Pr* (14)

(Freton et al., 2003). Besides, the electrostatic

(15)

º l

usual models are the Prandtl mixing length model and the *k*- ε model.

length model was chosen.  Boundary conditions**

2

where *κe* is the effective thermal conductivity and *Γ*¯ *e* is the electron mass diffusion that can be approximated by

$$
\overline{\Gamma}\_e \approx -\frac{m}{e'} \overline{J},
\tag{10}
$$

where *e*′ is the elementary electric charge and *m* is the electron mass. Equation (10) neglects the charge transported by ions. In (9) *he* = 5 *kB T* / (2 *m*) represents the specific electron enthalpy (*kB* is the Boltzmann's constant).

The effective viscosity is

$$
\mu\_{\mathfrak{e}} = \mu\_l + \mu\_t,\tag{11}
$$

and the effective thermal conductivity is

$$
\kappa\_c = \kappa + \frac{\mu\_t C\_p}{P\_r},
\tag{12}
$$

where *Cp*, *μl* and *κ* are the plasma specific heat at constant pressure, viscosity and thermal conductivity, respectively. The turbulent Prandtl number *Pr* and the turbulent viscosity *μt* are given in the section 3.5.

#### **3.4. Thermodynamic properties and transport coefficients**

The thermodynamic properties and transport coefficients data for a pure oxygen plasma in the temperature range 300 ÷ 30000 K (with a 100 K temperature intervals) and for nine different pressure values (0.1 ÷ 10 atm) were taken from (Murphy & Arundell, 1994). The source terms in (4) account for the Joule effect, the compression work, and the radiation loses 4 *π εN* , where *εN* was taken for a plasma radius of 0.5 mm (Freton et al., 2003). The NEC of pure oxygen for one atmosphere, has been multiplied by the factor *p* / *pATM* for other pressures (Zhou et al., 2009).

### **3.5. Turbulent model**

, comes

are

where *μe* is the effective viscosity and the 2/3 factor in the fluid dilatation term, ∂ *ul* / ∂ *xl*

º- Ñ +G k

G »- , ¢ *e*

mmm

is the elementary electric charge and *m* is the electron mass. Equation (10) neglects

,

and *κ* are the plasma specific heat at constant pressure, viscosity and thermal

m

conductivity, respectively. The turbulent Prandtl number *Pr* and the turbulent viscosity *μt*

The thermodynamic properties and transport coefficients data for a pure oxygen plasma in the temperature range 300 ÷ 30000 K (with a 100 K temperature intervals) and for nine different pressure values (0.1 ÷ 10 atm) were taken from (Murphy & Arundell, 1994). The source terms in (4) account for the Joule effect, the compression work, and the radiation loses 4 *π εN* , where *εN* was taken for a plasma radius of 0.5 mm (Freton et al., 2003). The NEC of pure oxygen for one atmosphere, has been multiplied by the factor *p* / *pATM* for

*r C*

k k= + *t p*

**3.4. Thermodynamic properties and transport coefficients**

*e*

the charge transported by ions. In (9) *he* = 5 *kB T* / (2 *m*) represents the specific electron enthalpy

where *κe* is the effective thermal conductivity and *Γ*¯

as

approximated by

72 Computational and Numerical Simulations

(*kB* is the Boltzmann's constant).

and the effective thermal conductivity is

The effective viscosity is

where *e*′

where *Cp*, *μl*

given in the section 3.5.

other pressures (Zhou et al., 2009).

from the Stokes hypothesis for the dilatation viscosity. The total heat flux in (4) describes the heat transported by conduction and the enthalpy transport by mass diffusion, and is defined

, *e ee q Th* (9)

*e* is the electron mass diffusion that can be

*m J e* (10)

= + , *elt* (11)

*P* (12)

The closure of the system equations requires extra relationships (which are commonly known as the turbulence model) to calculate the turbulent enhanced viscosity and thermal conduc‐ tivity. There are in the literature turbulence models of varying degrees of sophistication: the Reynolds stress model (RSM), the *k*- ε model and its variants, the renormalization group (RNG) *k*-ε model, the RNG *k*- ε model taking into account the low Reynolds number effect, the realizable *k*- ε model and the Prandtl mixing length model (Zhou et al., 2009). The two most usual models are the Prandtl mixing length model and the *k*- ε model.

Following previous published models (Freton et al. 2002; Freton et al., 2003), the Prandtl mixing length model was chosen. Such length is given as:

$$J\_m \equiv \mathcal{C} \mathcal{A},\tag{13}$$

where *c* is an adjustable parameter and λ is a local thermal radius which characterizes the boundary of the high velocity arc core, defined as the radial distance from the axis to the point at 2000 K (Yan et al., 1999). As inside the nozzle the radial temperature profile is very sharp (Prevosto et al., 2009c), λ results very close to the nozzle radius *RN*. It has been found that for transferred arcs the turbulent Prandtl number can be approximated by unity (Fang et al., 1994).

$$P\_r \equiv 1,\tag{14}$$

thus only the parameter *c* in (13) needs to be adjusted by comparing the numerical results with the experiment. The turbulent viscosity for isotropic turbulence was calculated taking into account the effect of the vortex injection (Freton et al., 2003)

$$
\mu\_t = \rho J\_m^{-2} \left( \left( \frac{\partial u\_x}{\partial \, \mathcal{Y}} \right)^2 + \left( \mathcal{Y} \frac{\partial}{\partial \, \mathcal{Y}} \left( \frac{u\_z}{\mathcal{Y}} \right) \right)^2 \right)^{1/2}. \tag{15}
$$

### **3.6. Boundary conditions**

Table 1 summarizes the prescribed values of the physical quantities (or its spatial derivatives) on the boundaries shown in Fig. 2. In addition, the voltage drop between the cathode AC and the anode FG was adjusted in order that the integrated value of the axial current density on a given section corresponds to the value of the electric current of the torch. An external source term to increase the temperature was applied at the axis of the torch AG to initiate the current. A current value of 30 A was used in this study, in according to the value used in the experi‐ ments. Also, at the hafnium insert AB the maximum value of the axial current density on the axis of the geometry was limited to ≤ 170 A mm−2 (Freton et al., 2003). Besides, the electrostatic potential value of the nozzle DE was calculated so as to preserve the zero current balance at its surface (i.e., the nozzle is electrically floating).

Finally, at the interface between the plasma and the anode, in order to maintain the conserva‐ tion of the energy flux and current intensity at this boundary, the following relations (neglect‐ ing radiation) were used to calculate the local thermal and electric conductivities

$$
\left[ -\kappa \left( \frac{\partial T}{\partial \mathbf{x}} \right) \right]\_{anode} = \left[ -\kappa \left( \frac{\partial T}{\partial \mathbf{x}} \right) \right]\_{plasma} + J\_x \left( \frac{\mathsf{S}}{2} \frac{k\_B}{e} (T - T\_{anode}) + \varphi\_A + \varphi\_w \right),
\tag{16}
$$

$$
\left[ -\sigma \left( \frac{\partial \phi}{\partial \mathbf{x}} \right) \right]\_{anode} = \left[ -\sigma \left( \frac{\partial \phi}{\partial \mathbf{x}} \right) \right]\_{planar},\tag{17}
$$

mass density at each position was then calculated from these initial pressure and temperature distributions using the equation of state. The electrostatic potential was set to zero initially. No initial distribution was required for the magnetic field as it is governed by an elliptic

For the external flow, the pressure within the domain was set to the ambient value of one atmosphere initially. The initial temperature was set to the ambient value throughout the domain. The initial value of the density was then evaluated from the temperature and pressure using the equation of the state. The electrostatic potential was set to zero initially. The specific

The set of governing equation was written in conservation form and discretized in time using a Taylor series first-order accuracy. These equations were then discretized in space using the finite volume method and solved with the given boundary conditions on a 81 15 non uniform internal grid and 39 47 non uniform external grid, by using the predictor-corrector algorithm (Ferziger &Períc, 2002; Fletcher, 1991). The time-step used in the time-marching algorithm was chosen so that the Courant-Friedrich-Levy criterion was fulfilled (Ferziger &Períc, 2002; Fletcher, 1991). The calculation was stopped when the following condition was achieved

values used for these initial guesses did not impact the final converged results.

( ) ( ) ( )

*t t*

 c

c

c

generating the results to be presented in the following section.

1

sufficient. Use of lower values for the convergence criterion resulted in negligible differences

The accuracy of the calculations was tested by repeating them with a 38 × 15 internal grid and 19 × 47 external grid. The change in the plasma temperature was everywhere less than 15 %, while the changes in the axial velocity were less than 20 %. The finer grid was then used for

This section is devoted to the torch model validation (for the temperature and the velocity) by comparing the model results with experimental data on these quantities obtained in our

For the temperature, its radial profile at 3.5 mm from the nozzle exit was used. This profile was derived from electrostatic probe measurements (Prevosto et al, 2008a, 2008b, 2009a) by using a rotating Langmuir probe system; and from a Schlieren technique (Prevosto et al, 2010) by using a Z-type optical configuration with a laser as light source. Both techniques give an experimental uncertainty of ≈ 10 % in the temperature values. For the axial velocity, two axial distributions (with an experimental uncertainty of ≈ 10 %) derived from a time-of-flight

3 10 ,

the value of variable *χ* at the time *t*. This convergence criterion was found to be

*t* (18)

Numerical Modelling of a Cutting Arc Torch http://dx.doi.org/10.5772/57045 75

equation (equation (7)).

being *χ* (*t*)

in the final results.

**4. Validation of the model**

Laboratory for the same cutting torch.

here *φA*, *φw* and *Tanode* are the anode voltage drop, the anode work function and the anode temperature; respectively (Gleizes et al; 2005).

**Table 1.** Model boundary conditions

### **3.7. Numerical aspects**

The unsteady form of (1) was solved using a time-marching method (Ferziger &Períc, 2002; Fletcher, 1991). Consequently, initial conditions had to be supplied in order to complete the formulation of the problem.

For the internal flow calculations the initial pressure distribution was prescribed as a linearly decreasing function of the axial position, from a specific value at the torch inlet to the atmos‐ pheric one at the exit. The fluid temperature was set to the ambient value everywhere, while the initial fluid velocity was given taking into account the mass flow conservation. The total mass density at each position was then calculated from these initial pressure and temperature distributions using the equation of state. The electrostatic potential was set to zero initially. No initial distribution was required for the magnetic field as it is governed by an elliptic equation (equation (7)).

For the external flow, the pressure within the domain was set to the ambient value of one atmosphere initially. The initial temperature was set to the ambient value throughout the domain. The initial value of the density was then evaluated from the temperature and pressure using the equation of the state. The electrostatic potential was set to zero initially. The specific values used for these initial guesses did not impact the final converged results.

The set of governing equation was written in conservation form and discretized in time using a Taylor series first-order accuracy. These equations were then discretized in space using the finite volume method and solved with the given boundary conditions on a 81 15 non uniform internal grid and 39 47 non uniform external grid, by using the predictor-corrector algorithm (Ferziger &Períc, 2002; Fletcher, 1991). The time-step used in the time-marching algorithm was chosen so that the Courant-Friedrich-Levy criterion was fulfilled (Ferziger &Períc, 2002; Fletcher, 1991). The calculation was stopped when the following condition was achieved

$$\frac{\mathbf{x}^{(t)} - \mathbf{x}^{(t-1)}}{\mathbf{x}^{(t)}} \le 10^{-3},\tag{18}$$

being *χ* (*t*) the value of variable *χ* at the time *t*. This convergence criterion was found to be sufficient. Use of lower values for the convergence criterion resulted in negligible differences in the final results.

The accuracy of the calculations was tested by repeating them with a 38 × 15 internal grid and 19 × 47 external grid. The change in the plasma temperature was everywhere less than 15 %, while the changes in the axial velocity were less than 20 %. The finer grid was then used for generating the results to be presented in the following section.


**3. Poverty in Africa**

Poverty is a multidimensional concept. According to the United Nations Development Programme (UNDP), poverty is not only the lack of income necessary to meet food and non-food needs (clothing, energy, housing) but also a lack of basic human capabilities (illiteracy, malnutrition, reduced life expectancy, poor maternal health, illness) [7]. Therefore poverty should not be considered only under the spectrum of financial income; as a result, the concept of poverty is difficult to quantify. But for a global assessment of poverty, a monetary scale has been developed as a common denominator between the different regions of the world in

**153**

associated complications [12].

contributions [13].

*Lifestyle and Epidemiology: Poverty and Cardiovascular Diseases a Double Burden in African…*

order to be able to assess poverty. According to the World Bank, the poverty line is considered to be 1.90 dollars per day per inhabitant since 2011 [8]. In 2015, the rate of the world's population living in poverty was 10%, representing 736 million people, more than half of whom live in SSA, on less than US\$1 a day [8, 9]. The advent of industrialization in China and India tremendously decreased the poverty rate unlike in SSA where progress in poverty has been limited. Of these 736 million poverty stricken population living on earth in 2015, 80% resided in SSA [10]. According to the World Bank's estimates, the global poverty rate slightly dipped to 8.6% in 2018. No isolated figure was reported for SSA. But since 2018, the World Bank has repeatedly reported that SSA will consistently record a poverty rate of at least two figures till the year 2030 unless very drastic interventions are put into

In several SSA countries, the direct care costs, are high in relation to household income, a major factor in poverty. The cost of HIV/AIDS treatment for an adult, combined with the loss of income due to absence from work, can push an entire household below the poverty line. Therefore, just as good health can stimulate economic growth, poor health can lead to poverty from which it is very difficult to escape. The vicious cycle of poverty and poor health is observed in many African countries. About 76% of people in SSA have an income of less than US\$2 per day and 46.5% have an income of less than US\$1.08 per day [9]. While poverty has been declining in other parts of the world such as East and South Asia over the two decades the trend is clearly reversed in SSA. Between 1981 and 2001, the domestic product of SSA countries fell by 13% and the number of people in this region living on less than US\$1 per day doubled from 164 million to 314 million. While Africans accounted for only 16% of the world's poor population in the year 1985, the propor-

*DOI: http://dx.doi.org/10.5772/intechopen.95785*

place to address the problem of poverty in SSA [10].

tion rose to 31% by 1998, and this trend is expected to continue [9].

**4. Cost of management of cardiovascular disease in Africa**

In Africa, the cost of management is variable. With regard to hypertension, the overall average daily cost of drug treatment for uncomplicated hypertension is estimated at 368 ± 234.6 FCFA, i.e. 0.68 ± 0.44 dollars, representing more than a third of the daily income (1.90 dollars) [11]. In view of the cost of treatment, the absence of symptoms associated with hypertension is often the cause of non-adherence to treatment. Also, some patients who often reach the stages of complications of CVDs often experience the cost of treatment increased by the additional cost of treating the

In Africa, 60–70% of health expenditure is paid by households directly to health facilities, compared to a global average of 46%. This may be due to the preponderance of the informal sector (farmers, craftsmen,…) which groups together more than 70% of the African population who are not covered by health insurance. Contrary to those in the informal sector, some African governments are setting up compulsory health insurance systems for the formal sector, civil servants or employees of private companies, financed through employee and employer

**5. Poverty, malnutrition and cardiovascular disease: a vicious cycle**

Poverty is one of the socio-economic factors at the root of malnutrition in Africa. The prevalence of malnutrition in SSA rose from 181 million in 2010 to 222 million in 2016 [14]. Poverty and malnutrition are part of a vicious circle. Poverty

*Lifestyle and Epidemiology: Poverty and Cardiovascular Diseases a Double Burden in African… DOI: http://dx.doi.org/10.5772/intechopen.95785*

order to be able to assess poverty. According to the World Bank, the poverty line is considered to be 1.90 dollars per day per inhabitant since 2011 [8]. In 2015, the rate of the world's population living in poverty was 10%, representing 736 million people, more than half of whom live in SSA, on less than US\$1 a day [8, 9]. The advent of industrialization in China and India tremendously decreased the poverty rate unlike in SSA where progress in poverty has been limited. Of these 736 million poverty stricken population living on earth in 2015, 80% resided in SSA [10]. According to the World Bank's estimates, the global poverty rate slightly dipped to 8.6% in 2018. No isolated figure was reported for SSA. But since 2018, the World Bank has repeatedly reported that SSA will consistently record a poverty rate of at least two figures till the year 2030 unless very drastic interventions are put into place to address the problem of poverty in SSA [10].

In several SSA countries, the direct care costs, are high in relation to household income, a major factor in poverty. The cost of HIV/AIDS treatment for an adult, combined with the loss of income due to absence from work, can push an entire household below the poverty line. Therefore, just as good health can stimulate economic growth, poor health can lead to poverty from which it is very difficult to escape. The vicious cycle of poverty and poor health is observed in many African countries. About 76% of people in SSA have an income of less than US\$2 per day and 46.5% have an income of less than US\$1.08 per day [9]. While poverty has been declining in other parts of the world such as East and South Asia over the two decades the trend is clearly reversed in SSA. Between 1981 and 2001, the domestic product of SSA countries fell by 13% and the number of people in this region living on less than US\$1 per day doubled from 164 million to 314 million. While Africans accounted for only 16% of the world's poor population in the year 1985, the proportion rose to 31% by 1998, and this trend is expected to continue [9].