**6.2 Method of implementation**

shown by **Figure 8**, in which system cost (*SC*) increases as the reliability level increases. At the same time, the outage cost (*OC*) decreases because of reliability improvement and adequate generating capacity additions. The most optimal reliability levels vary between 0.07 and 0.13 days/year (see **Figure 8**). However, in some cases adding new capacity may not signify the ideal solution to meet increasing future loads and maintain enhanced reliability levels. Therefore, it is better to improve an operating unit's performance through regular preventive maintenance. Likewise, establishing a good cooperation between the supply side (electric company) and the demand side (the customers) through well-coordinated load management strategies may further improve financial performance (1£ = 4.5 SR).

**6. Applications of reliability indices in power system interconnection**

• When connecting isolated electrical systems, each system needs a lower generation reserve than the reserve when it is isolated and at a better level of

• When interconnecting isolated electrical systems, it is possible to share the available reserve so that each system maintains a lower level of reserve before being interconnected. This will result in both lower installation costs (fixed

• The electrical connection reduces the fixed and operating costs of the total

• In emergency and forced outage conditions, such as breakdowns, multiple interruptions, and the simultaneous discharge of several generators, which may cause a capacity deficit that is incapable of coping with current loads and possibly a total breakdown of the electrical system as a whole, electrical interconnection helps to restore the state of stability and reliability of electrical

• The interconnection of power systems enables the exchange of electrical energy in a more economical manner, as well as the exchange of temporal energy and the utilization of the temporal variation in energy demand.

• The electrical connection through the construction of larger power plants with higher economic return and reliability increases the degree of cooperation and the sharing of potential opportunities and possibilities that are available

• By nature, the various loads do not have peak values at the same time. As a result of this variation in peak loads (maximum demands), the load of the interconnected systems is less than the total load of each system separately,

thus reducing and saving the total power reserve for systems.

costs) and decreased operation costs (variable costs).

A review of the main advantages of electrical interconnection between electrical

**6.1 Introduction**

reliability.

installed capacity.

between the electrical systems.

systems.

**154**

power systems is summarized as follows:

*Reliability and Maintenance - An Overview of Cases*

The above brief review of the main advantages and merits of electrical interconnection from an economic and technical point of view highlights the usefulness and importance of conducting electrical interconnection studies between the systems as they relate to the cost of capital and operational costs on the one hand and the improvement of their levels and performance on the other. Such studies are especially significant after the completion of the infrastructure of electrical systems. Indeed, the next step is to seriously consider linking electrical systems through unified national networks throughout the widespread Kingdom.

Most power systems have interconnections with neighboring systems. The interconnection reduces the amount of generating capacity required to be installed as compared with that which would be required without the interconnection. The amount of such reduction depends on the amount of assistance that a system can get, the transfer capability of the tie-line, and the availability of excess capacity reserve in the assisting systems.

One objective to be mentioned in this context is to evaluate the reliability benefits associated with the interconnection of electric power systems. Therefore, this study is focused on the reliability evaluation of two systems that may be viewed upon as both isolated systems and as interconnected systems. The analysis of this type explores the benefits that may accrue from interconnecting systems rather than being isolated as well as deciding viable generation expansion plans.

A 5-year expansion plan for systems A and B assuming a reliability criterion of 0.1 days/year (0.1–0.6 frequently quoted as appropriate values in most industrial countries) was determined. The analysis represents the expansion plans for both systems as being isolated and interconnected. An outcome of these expansion plans is shown in **Figure 9**.

If the two systems (A and B) are reinforced whenever the reliability index (risk level) falls below the prescribed level (i.e., ) at any year of the planning horizon, the results shown in the following table exhibits that the number

**Figure 9.** *LOLE levels before and after systems interconnection.*

of added units and their cost are reduced if the two system are interconnected rather than being isolated.

The expansion of the electricity sector during the last three decades has resulted in the many electricity companies throughout the Kingdom being integrated into what was known, for a short time, as "the Saudi Consolidated Electric Companies (SCECOs)." These companies later merged into a single more reliable, efficient, and less expensive company known as the "Saudi Electricity Company (SEC)." Moreover, some areas (Eastern and Central) have been linked via a tie-line in order to prepare for the integration of the entire Kingdom under a unified national network. Experts and planners of electrical power systems find it economically and technically unfeasible to increase the electrical capabilities of electric power plants that are often isolated, dispersed, and distant. However, after the completion of the structures of these systems, the next and natural step, to achieve advantages and benefits, is to connect these electric power systems to each other through unified transmission networks. Undoubtedly, linking these power systems will both reduce the cost of construction and provide reserve and fuel, all while increasing the strength of the electrical system and maximizing its capability to meet current and

One practical example demonstrating the evolving of industry of electric sector in the Kingdom of Saudi Arabia will be shown in this section. The availability of network can be analyzed in a similar manner to that used in generating capacity evaluation (Section 3.1). Therefore, the probability of failing to satisfy the criterion of service adequacy and continuity can be evaluated. Provided the appropriate component reliability indices are known, it is relatively simple to evaluate the expected failure rate (*λ*) of the system, the average duration of the outage I, and the unavailability or annual outage time (*U*). To do this, the values of *λ*, *r*, and *U* are

The state-space transition diagram for a two-component system is shown in

*λ*þ*μ*.

(10)

*μ*1 þ *λ*1

*μ*1 þ *λ*1

*μ*1 þ *λ*1

*μ*1 þ *λ*1

� *μ*2 *μ*2 þ *λ*2

� *μ*2 *μ*2 þ *λ*2

� *λ*2 *μ*2 þ *λ*2

� *λ*2 *μ*2 þ *λ*2

The probability of a component being in the up state is . Also, the probability of a component being in the down state is *λ*

Probability of being in state 1 ¼ *μ*1

Probability of being in state 2 ¼ *λ*1

Probability of being in state 3 ¼ *μ*1

Probability of being in state 4 ¼ *λ*1

The most accurate method for analyzing networks including weather states is to use the Markov modeling. However, this becomes impractical for all except the simplest system. Instead, therefore, an approximate method is used based upon

future electric loads.

*Reliability Evaluation of Power Systems DOI: http://dx.doi.org/10.5772/intechopen.85571*

**7.3 Practical example**

*7.3.1 State probabilities*

simple rules of probability.

**157**

**Figure 10**.

required for each component of the system.

System costs as isolated and interconnected:

Therefore, it can be concluded from the above analysis that both systems will benefit from the interconnection. The reliability of both systems can be improved, and consequently the cost of service will be reduced through interconnection and reserve sharing. However, this is not the overall saving because the systems must be linked together in order to create an integrated system. The next stage must, therefore, assess the economic worth that may result from either interconnection or increasing generating capacity individually and independently.


**2.6 Xylanase activity assay**

Dinitrosalicylic acid (DNS) solution was prepared in the following manner. Solution A was prepared by mixing 300 mL of 4.5 % NaOH, 880 mL of 1 % 3,5- DNS and 225 g of potassium sodium (+)-tartrate tetrahydrate. For the preparation of solution B, 22 mL of 10 % NaOH and 10 g of phenol was mixed and filled up to 100 mL. To 69 mL of the mixture, 6.9 g of NaHCO3 was added. Solutions A and B were mixed thoroughly and placed at room temperature for 2 days. After filtration, the mixture was used as DNS solution.

Xylanase activity was determined by measuring the amount of reducing sugar released from xylan. One hundred μL of enzyme sample was added to 1 mL of 1 % xylan in 100 mM sodium phosphate buffer (pH 6.5) in a test tube (15 mmΦ × 10.5 cm) and incubated statically at 50°C for 5 min. Two mL of DNS solution was added and cooled immediately in an ice bath. Then the test tubes were boiled for 5 min and cooled in an ice bath. After centrifugation at 18,000×*g* at 4°C for 5 min, absorbance of the supernatant at 540 nm was measured by spectrophotometer (UV2400; Shimadzu, Kyoto, Japan). Xylose was used as the standard. One unit (U) of xylanase activity was defined as the amount of enzyme that liberates 1 μmol of reducing sugars (xylose equivalent) per min.

### **2.7 Measurement of xylanase activity during SSF**

SSF was carried out as described in Section 2.2 without addition of glucose. One gram of solid culture sample and 9 ml of sterile distilled water were mixed in a sterile 18-mmdiameter test tube, the test tube was vortexed thoroughly and shaken at 150 spm for 5 min at room temperature. The suspension was centrifuged at 18,000 ×*g* at 4 °C for 10 min and the supernatant obtained was used for xylanase assay.

#### **2.8 Measurement of concentration of protein**

Protein concentrations were determined by the Bradford method (Bradford, 1976) with the Protein Assay Kit II (Bio-Rad, Tokyo, Japan) with bovine serum albumin as the standard protein.

#### **2.9 Purification of xylanase**

Solid cultures (90 g) incubated for 5 days in SSF were mixed with 900 mL of distilled water and stirred for 10 min. The suspension was centrifuged at 6,500×*g* at 4°C for 20 min and the supernatant was frozen at -20°C and then thawed. The sample was centrifuged for removal of polysaccharides under the same condition. Ammonium sulfate was added to the

diameter× 100 mm height, Merck, Germany) to determine iturin A concentrations. The HPCL system was operated at a flow rate of 2.0 mL/min with acetonitrile-10 mM ammonium acetate (65:35 [vol/vol]) at a column temperature of 40°C. The elution was monitored at 205 nm by a UV detector (880-UV, Intelligent UV/VIS Detector, Jasco, Tokyo,

Although iturin A has 8 homologues with different side-chain structures (Asaka & Shoda, 1996), the concentration of iturin A was defined as the total amount of five major homologues. The correlation between the peak heights and the concentration of pure iturin A (Sigma-Aldorich, Tokyo, Japan) was used for quantification. Iturin A concentration was

Dinitrosalicylic acid (DNS) solution was prepared in the following manner. Solution A was prepared by mixing 300 mL of 4.5 % NaOH, 880 mL of 1 % 3,5- DNS and 225 g of potassium sodium (+)-tartrate tetrahydrate. For the preparation of solution B, 22 mL of 10 % NaOH and 10 g of phenol was mixed and filled up to 100 mL. To 69 mL of the mixture, 6.9 g of NaHCO3 was added. Solutions A and B were mixed thoroughly and placed at room

Xylanase activity was determined by measuring the amount of reducing sugar released from xylan. One hundred μL of enzyme sample was added to 1 mL of 1 % xylan in 100 mM sodium phosphate buffer (pH 6.5) in a test tube (15 mmΦ × 10.5 cm) and incubated statically at 50°C for 5 min. Two mL of DNS solution was added and cooled immediately in an ice bath. Then the test tubes were boiled for 5 min and cooled in an ice bath. After centrifugation at 18,000×*g* at 4°C for 5 min, absorbance of the supernatant at 540 nm was measured by spectrophotometer (UV2400; Shimadzu, Kyoto, Japan). Xylose was used as the standard. One unit (U) of xylanase activity was defined as the amount of enzyme that

SSF was carried out as described in Section 2.2 without addition of glucose. One gram of solid culture sample and 9 ml of sterile distilled water were mixed in a sterile 18-mmdiameter test tube, the test tube was vortexed thoroughly and shaken at 150 spm for 5 min at room temperature. The suspension was centrifuged at 18,000 ×*g* at 4 °C for 10 min and the

Protein concentrations were determined by the Bradford method (Bradford, 1976) with the Protein Assay Kit II (Bio-Rad, Tokyo, Japan) with bovine serum albumin as the standard

Solid cultures (90 g) incubated for 5 days in SSF were mixed with 900 mL of distilled water and stirred for 10 min. The suspension was centrifuged at 6,500×*g* at 4°C for 20 min and the supernatant was frozen at -20°C and then thawed. The sample was centrifuged for removal of polysaccharides under the same condition. Ammonium sulfate was added to the

temperature for 2 days. After filtration, the mixture was used as DNS solution.

liberates 1 μmol of reducing sugars (xylose equivalent) per min.

**2.7 Measurement of xylanase activity during SSF**

supernatant obtained was used for xylanase assay.

**2.8 Measurement of concentration of protein**

expressed as μg/ g initial wet soybean curd residue.

**2.6 Xylanase activity assay**

Japan).

protein.

**2.9 Purification of xylanase**

supernatant to 30 % saturation, and the precipitate was removed by centrifugation. Then, ammonium sulfate was added to 70 % saturation. The precipitate was recovered by centrifugation, suspended in 50 mM MES buffer (pH 6.0) and dialyzed overnight against the same buffer. Then the sample was concentrated by ultrafiltration with YM10 (molecular mass cut-off 10 kDa; Advantec, Tokyo, Japan).

The concentrate was applied to a CM-Toyopearl column (1.3 cm Φ×8.3 cm; Tosoh, Tokyo, Japan) pre-equilibrated with buffer A (50 mM MES buffer, pH 6.0), and fractions were eluted with a continuous linear gradient of 0-0.5 M NaCl in buffer A (total volume 120 mL). The flow speed and the volume of one fraction were 4 mL/min and 8 mL, respectively. In this process, xylanase activity was detected in two fractions, one of which was trapped in the column (Fraction I) and the other was not trapped in the column but passed through (Fraction II). These fractions were subjected to further purification processes.

Fraction I was concentrated using Centriprep YM-10 (molecular mass cut-off 10 kDa; Millipore, Tokyo, Japan), diluted with buffer A and applied to a RESOURCES column (0.6 cm Φ×3.0 cm; Pharmacia Biotech, Uppsala, Sweden) pre-equilibrated with buffer A. Fractions were eluted with a continuous linear gradient of 0-0.15 M NaCl in buffer A (total volume 30 mL). The flow speed and the volume of one fraction were 1 mL/min and 1 mL, respectively. The xylanase active fractions were concentrated with Centriprep YM-10 and applied to a Superdex 75 column (1.6Φ×60 cm; Amersham Bioscience, Tokyo, Japan) preequilibrated with buffer A containing 0.2 M NaCl. The elution was carried at a flow rate of 1 mL/min and a volume of one fraction was 2 mL.

The pH of the Fraction II was adjusted to 9.5 by adding NaOH and applied to a QAE-Toyopearl (1.6Φ×3.7 cm; Tosoh) pre-equilibrated with buffer B (25 mM piperazine buffer, pH 9.5), and fractions were eluted with a continuous linear gradient of 0-0.5 M NaCl in buffer B (total volume 120 mL). The flow speed and the volume of one fraction were 4 mL/min and 8 mL, respectively. The xylanase active fractions were concentrated with Centriprep YM-10, and fractions were diluted with buffer B and applied to a QAE column. Step elution was performed with 0.07 M NaCl (total elution volume 96 mL). The flow speed and the volume of one fraction were 4 mL/min and 8 mL, respectively.

The xylanase active fractions were supplied to the subsequent Butyl-Toyopearl chromatography. A column of Butyl-Toyopearl (1.6Φ×4.5 cm; Tosoh) pre-equilibrated with 25 mM piperazine buffer containing 1 M ammonium sulfate was used. Ammonium sulfate was added to the active fractions and its concentration was adjusted to 1 M. This solution was then applied to the column and the elution was carried out with a linear gradient of 1-0 M ammonium sulfate in 25 mM Piperazine buffer (total volume 180 mL). The flow speed and the volume of one fraction were 4.5 mL/min and 9 mL, respectively.


*3.1. Accuracy of MERRA-2 AOD*

As AOD are retrieved and assimilated from AERONET, MISR, MODIS, and AVHRR, MERRA-2 AOD agreed well with the ground-based measurements [45]. The correlation coefficients between AERONET and MERRA-2 AOD were 0.84, 0.88, and 0.90 in Xianghe, Beijing, and the Yangtze River Basin [46]. MERRA-2 AOD was compared with groundbased AOD from 29 CARSNET stations throughout China during 2002–2014, and good agreement was also obtained [47]. The good agreement between MERRA-2 and groundbased AOD offered an important theoretical basis for the following study of temporal and spatial distributions of MERRA-2 AOD over the SCS from 1980 to 2020.


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. © 2018 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.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

One of the fundamental challenges faced by refugee children in schools is adaptation to a new curriculum. Children will be accustomed to the curriculum used in their home country, which could have striking differences with the one they have to follow in the host country. Issues faced by refugee learners include having to adapt to the new curriculum in the host country [6]. French-speaking Black African-born students who entered Canada as refugees were integrated in Canadian schools [7]. They viewed the curricula as incompatible with their needs and what they were used to studying.

There is an increasing recognition that many educational environments have been failing to meet the needs of refugee children, especially curriculum related, such as assisting them to adapt [8]. Learners are often mainstreamed in schools, and it is up to them to adapt. Some children find it hard to fit into the new educational system, which results in frustration and failure to perform in school. Refugee children who went to attend schooling in Australia had problems with the curriculum, which was new and completely different from what they were used to studying. This resulted in frustration with, and alienation from, their mainstream schools [9].

In a situation where refugee children struggle to come to terms with curricula in the host country, schools have a critical role to play in helping learners to have a smooth curricular transition from their home to the host country [10]. Learners require additional support from teachers so that they understand differences that exist between what they used to study and what they will actually be studying. Zimbabwean refugee learners did not receive any form of support to adapt to a new curriculum when they joined a school of refugees in South Africa. Children were used to following their localised Zimbabwean curriculum, which was not the same as the Cambridge curriculum, which they were using at a school of refugees in South Africa.

In order to understand Zimbabwean learners' experiences of curricular transition, it is critical to illuminate the curriculum changes that occurred in their country (Zimbabwe). This is important because learners who joined a refugee school in South Africa were familiar with the Zimbabwean curriculum, which was developed along the lines of the Cambridge system.

Before Zimbabwe gained independence in 1980, its curricula, including examinations, were controlled by the University of Cambridge in the United Kingdom [11]. Shortly after Zimbabwe gained its independence, the country was determined to run its curricula and set its own examinations locally. There was a smooth transition of the curriculum from Cambridge to Zimbabwe School Examinations Council (ZIMSEC).

The localisation of examinations occurred from 1984 to 1994, and emphasis was initially on the ordinary-level examinations [12]. Refugee children who participated in this study did not have experience in the Cambridge curriculum while they were in Zimbabwe. Some were born in 1995, the time when localisation had already begun. However, their education was heavily inspired by the lingering influence of the Cambridge curriculum in Zimbabwe [11].

#### **1.1. Theoretical framework**

One of the fundamental challenges faced by refugee children in schools is adaptation to a new curriculum. Children will be accustomed to the curriculum used in their home country, which could have striking differences with the one they have to follow in the host country. Issues faced by refugee learners include having to adapt to the new curriculum in the host country [6]. French-speaking Black African-born students who entered Canada as refugees were integrated in Canadian schools [7]. They viewed the curricula as incompatible with their needs

There is an increasing recognition that many educational environments have been failing to meet the needs of refugee children, especially curriculum related, such as assisting them to adapt [8]. Learners are often mainstreamed in schools, and it is up to them to adapt. Some children find it hard to fit into the new educational system, which results in frustration and failure to perform in school. Refugee children who went to attend schooling in Australia had problems with the curriculum, which was new and completely different from what they were used to studying. This resulted in frustration with, and alienation from, their mainstream

In a situation where refugee children struggle to come to terms with curricula in the host country, schools have a critical role to play in helping learners to have a smooth curricular transition from their home to the host country [10]. Learners require additional support from teachers so that they understand differences that exist between what they used to study and what they will actually be studying. Zimbabwean refugee learners did not receive any form of support to adapt to a new curriculum when they joined a school of refugees in South Africa. Children were used to following their localised Zimbabwean curriculum, which was not the same as the Cambridge curriculum, which they were using at a school of refugees in South

In order to understand Zimbabwean learners' experiences of curricular transition, it is critical to illuminate the curriculum changes that occurred in their country (Zimbabwe). This is important because learners who joined a refugee school in South Africa were familiar with the Zimbabwean curriculum, which was developed along the lines of the Cambridge

Before Zimbabwe gained independence in 1980, its curricula, including examinations, were controlled by the University of Cambridge in the United Kingdom [11]. Shortly after Zimbabwe gained its independence, the country was determined to run its curricula and set its own examinations locally. There was a smooth transition of the curriculum from Cambridge to

The localisation of examinations occurred from 1984 to 1994, and emphasis was initially on the ordinary-level examinations [12]. Refugee children who participated in this study did not have experience in the Cambridge curriculum while they were in Zimbabwe. Some were born in 1995, the time when localisation had already begun. However, their education was heavily inspired by the lingering influence of the Cambridge curriculum in

Zimbabwe School Examinations Council (ZIMSEC).

and what they were used to studying.

schools [9].

138 Immigration and Development

Africa.

system.

Zimbabwe [11].

A theoretical framework guiding this study is the Bronfenbrenner's Social Ecological Model. At the heart of the Social Ecological Model is a view that interaction of people in different systems is inevitable in a developing child [13]. Similarly, interaction of refugee learners is inevitable when they strive to adapt to a new curriculum in the host country. An experience of curricular transition among refugee children is a product of interaction among different stakeholders [14]. The model highlights that during the process of human growth and development, a person interacts with microsystems, mesosystems, exosystems, macrosystems and chronosystems [15].

The microsystem entails a child's interaction with proximal settings of parents, teachers, principal and peers [13]. Mesosystem is a system that shows the interaction of microsystems [16]. An exosystem is defined as: "One or more settings that do not involve the developing person as an active participant, but in which events occur that affect, or are affected by, what happens in the setting containing the developing person" [15]. The exosystem also refers to the influence that a community has [16].

The macrosystem can be seen as the norms, values, attitudes, beliefs and ideologies, which someone gets from the society in which he/she lives. It can be viewed as a societal blueprint for a particular culture [15]. The chronosystem summarises the length of time and how it relates to the interactions between micro-, meso-, exo- and macrosystems and their influences on the growth and development of a child [14].

## **2. Methodology**

The study adopted a qualitative research approach. The approach was ideal because it allowed the researcher to collect data by interacting extensively and closely with participants during the study. Qualitative research enables a researcher to interact with respondents in order to gain insight about the nature of a particular phenomenon [17].

The paradigmatic position for this study was interpretive. Every qualitative research has an interpretive perspective, which focuses on uncovering participants' views [18]. The paradigm was chosen because it allowed the researcher to acquire information by engaging in a dialogue with participants. The study was conducted in the form of a case study design. A case study was preferred because it provides an in-depth description and exploration of a specific subject that is under study [19]. The study was conducted at a refugee school in Johannesburg, South Africa. The school has accompanied and unaccompanied refugee children from different African countries. It has both primary and secondary education, which follows Curriculum Assessment Policy Statement (CAPS) and the Cambridge curriculum, respectively.

In almost all qualitative research, purposive sampling is adopted in which researchers use their judgement to select a sample that they believe, based on prior information, will provide the data they need [20]. In this study, "purposive sampling", a qualitative sampling procedure which allows the researcher to deliberately select participants, a learning site and research techniques, was used [21]. Purposive sampling was used to select 10 participants: one principal, four teachers and five learners. The principal was selected to explain how and why the school adapted the Cambridge curriculum. Teachers were selected to elucidate learners' experiences of curricular transition. Zimbabwean learners who were in form four were selected to explain their experiences of changing curricula from ZIMSEC to Cambridge.

Data were collected using documentary reviews, semi-structured interviews with each of the participants and a focus group discussion with all learners. Data were analysed using content analysis. Ethical issues were observed by obtaining ethical clearances from the university and refugee school. The purpose of the study was explained to all participants. They were informed that they were free to withdraw from the study at any point in time. Consent forms were signed, and pseudonyms were used to ensure confidentiality. Validity and trustworthiness were ensured by a pilot study, which was done to test the instruments. Transcribed data were taken back to participants to show how their voices were captured. This was done to enhance trustworthiness of the study.

## **3. Findings**

#### **3.1. Curriculum at a refugee school**

The school offers a full educational programme for primary and secondary education to children of all ages. The following subjects are taught at Chitate Street School of Refugees (pseudonym): Maths, English language, Science, Life skills/orientation, Computers, Art and craft, Music, Drama, Physical education, Commerce, Geography, History, English literature, Bible knowledge/Divinity, Accounts, Business Management and Sociology. The refugee curriculum was slightly modified by the school management team to incorporate life skills/orientation, computer studies, music and drama, arts and physical education, which are done by learners from Grade 3 to Form 4 [22].

According to the principal, primary and secondary school learners do different curricula at the school. The primary level, which extends from Grades 1 to 7, follows South Africa's CAPS. The secondary school level follows the Cambridge curriculum, which is completely different from the CAPS. The principal said: "The decision to use Cambridge in the secondary school was agreed upon by the school (teachers and Bishop) and refugee community".

The principal explained reasons why the school decided to adapt the Cambridge curriculum:

The school teachers and refugee community decided to follow the Cambridge curriculum for three main reasons:

**i.** The Cambridge curriculum is international. Certificates obtained through Cambridge are accepted everywhere in the world. Since the school has children from 12 different countries, it was agreed by the Bishop, parents and teachers and refugee community that the Cambridge curriculum was better than CAPS because it enables children to go back to their home countries and integrate into tertiary education or the job market without problems.

The Cambridge curriculum is studied by learners who are in secondary school. Whenever it is examination time, the school registers with the British Council, which is located in Johannesburg.

#### *3.1.1. Refugee learners' experiences of curricular transition*

procedure which allows the researcher to deliberately select participants, a learning site and research techniques, was used [21]. Purposive sampling was used to select 10 participants: one principal, four teachers and five learners. The principal was selected to explain how and why the school adapted the Cambridge curriculum. Teachers were selected to elucidate learners' experiences of curricular transition. Zimbabwean learners who were in form four were selected to explain their experiences of changing curricula from ZIMSEC to Cambridge.

Data were collected using documentary reviews, semi-structured interviews with each of the participants and a focus group discussion with all learners. Data were analysed using content analysis. Ethical issues were observed by obtaining ethical clearances from the university and refugee school. The purpose of the study was explained to all participants. They were informed that they were free to withdraw from the study at any point in time. Consent forms were signed, and pseudonyms were used to ensure confidentiality. Validity and trustworthiness were ensured by a pilot study, which was done to test the instruments. Transcribed data were taken back to participants to show how their voices were captured. This was done to

The school offers a full educational programme for primary and secondary education to children of all ages. The following subjects are taught at Chitate Street School of Refugees (pseudonym): Maths, English language, Science, Life skills/orientation, Computers, Art and craft, Music, Drama, Physical education, Commerce, Geography, History, English literature, Bible knowledge/Divinity, Accounts, Business Management and Sociology. The refugee curriculum was slightly modified by the school management team to incorporate life skills/orientation, computer studies, music and drama, arts and physical education, which are done by

According to the principal, primary and secondary school learners do different curricula at the school. The primary level, which extends from Grades 1 to 7, follows South Africa's CAPS. The secondary school level follows the Cambridge curriculum, which is completely different from the CAPS. The principal said: "The decision to use Cambridge in the secondary school was agreed upon by the school (teachers and Bishop) and refugee community".

The principal explained reasons why the school decided to adapt the Cambridge curriculum: The school teachers and refugee community decided to follow the Cambridge curriculum for

**i.** The Cambridge curriculum is international. Certificates obtained through Cambridge are accepted everywhere in the world. Since the school has children from 12 different countries, it was agreed by the Bishop, parents and teachers and refugee community that the Cambridge curriculum was better than CAPS because it enables children to go back to their home countries and integrate into tertiary education or the job market without problems.

enhance trustworthiness of the study.

**3.1. Curriculum at a refugee school**

learners from Grade 3 to Form 4 [22].

three main reasons:

**3. Findings**

140 Immigration and Development

There are many issues occurring around the curriculum at Chitate Street School. Refugee learners from Zimbabwe experienced what can be described as curriculum switching. Every Zimbabwean learner at Chitate Street School changed curricula at least twice. That is, from ZIMSEC offered in Zimbabwe to Cambridge, which is studied at a refugee school in South Africa. One may think that refugee children had a smooth curricular transition from ZIMSEC to Cambridge because the two curricula have a lot of similarities since the latter influenced the former. Despite so many similarities between Cambridge and ZIMSEC, all teachers unanimously agreed that curricular switching experienced by children affected their performance. Refugee learners from Zimbabwe experienced contextual, content and conceptual differences between ZIMSEC and Cambridge.

#### *<IP_ADDRESS>. Learners' contextual experiences of curricula*

ZIMSEC and Cambridge curricula use different contextual orientations. While ZIMSEC contextualises its phenomena to Southern African countries in general, and Zimbabwe in particular, Cambridge focuses on global issues. Where learners would give western examples in the Cambridge curriculum, they are required to use local examples (from Zimbabwe and Southern Africa) in the ZIMSEC. In all subjects, ZIMSEC would require learners to have comprehensive understanding of issues surrounding Southern Africa and to have a little bit of reference to Western countries. This is contrary to Cambridge which requires learners to understand what is happening in the whole world including all African countries.

In Geography, the Cambridge curriculum is designed in a way that children learn world Geography, which makes them imagine things in a world view. A geography teacher said:

*Cambridge curriculum is designed in a way that children learn topography of the whole world for example, prairies of Canada. On the contrary, ZIMSEC required children to be in touch with reality of geographical features in Southern Africa. For example, they learnt about Table Mountain in Cape Town, South Africa or Mountain Kilimanjaro in Tanzania.*

Zimbabwean children who were used to localised information in the ZIMSEC had a challenge of adjusting to the world view, which is a pre-requisite of the Cambridge curriculum. Children struggle to understand the switch of curricula from locally based to international examples. There was a similar challenge in conducting experiments in science. A science teacher said:

*My learners were used to ZIMSEC where they would use locally available plants such as a potato when carrying out an experiment of osmosis in science. This is different from Cambridge which requires learners to use rubab (a foreign plant) to demonstrate the movement of molecules from a region of high to low water concentration. Children did not know what rubab was. They thought that osmosis could be done with a potato only. They did not know that the use of a potato in ZIMSEC was a way of using readily available fleshy plants. Such minor differences confuse children and they require a lot of help to fully understand the Cambridge curriculum.*

Learners' confusion about the curricular switching happens at different levels, depending on how long they have been doing ZIMSEC. A learner who was doing ZIMSEC longer is likely to be more confused because he/she is used to localised information. A geography teacher gave an example of a student who experienced learning through ZIMSEC longer than the Cambridge curriculum. The teacher said:

*One student joined the school from Zimbabwe a few months before writing Cambridge examinations. He did not do well in the geography examination although he had all the notes that he got from his teachers in Zimbabwe. He did not know that he was supposed to have a broader view since it was going to be Cambridge he was going to sit for.*

Another teacher challenged the view that learners with a long experience of ZIMSEC are likely to find it more difficult at Chitate Street School. The teacher argued that ZIMSEC is more challenging than Cambridge. Hence, a child who did ZIMSEC longer is likely to find Cambridge easier as long as he understands contextual differences, which exist between the two curricula. In some instances, it was noted that major curricula differences, which children were experiencing, were as a result of the content.

#### *<IP_ADDRESS>. Learners' experiences of curricula content*

Refugee children experienced a slight change of content when they changed curriculum from ZIMSEC to Cambridge. There are some minor differences, which exist between ZIMSEC and Cambridge curricula in terms of content. There are some topics that are in ZIMSEC but not in the Cambridge curriculum. Sometimes both curricula may have a common topic, but the depth of content would be different.

#### A science teacher said:

*A challenge that Zimbabwean children had is that when they first see a topic that the teacher was going to teach, they think that it will be easy and it contains everything that they were doing in their country. Some children may say that they had already covered the topics and may not take the lesson seriously because they had the background. But, when I did a revision with them, they began to wonder and ask where some of the unfamiliar information was coming from. An example of this is, children used to work out only word equations in the ZIMSEC syllabus, but they are required to work out both word and chemical equations in Cambridge. That confuses learners. They wonder where some unfamiliar topics and concepts were emerging from.*

The transition of curricula from ZIMSEC to Cambridge is a big challenge to learners because they were used to studying basic ideas about specific topics. This is different from the Cambridge approach, which is emphatic on some themes. Sometimes learners would not know the areas that they have to study in-depth. One learner said:

Zimbabwean children who were used to localised information in the ZIMSEC had a challenge of adjusting to the world view, which is a pre-requisite of the Cambridge curriculum. Children struggle to understand the switch of curricula from locally based to international examples. There was a similar challenge in conducting experiments in science. A science teacher said:

*My learners were used to ZIMSEC where they would use locally available plants such as a potato when carrying out an experiment of osmosis in science. This is different from Cambridge which requires learners to use rubab (a foreign plant) to demonstrate the movement of molecules from a region of high to low water concentration. Children did not know what rubab was. They thought that osmosis could be done with a potato only. They did not know that the use of a potato in ZIMSEC was a way of using readily available fleshy plants. Such minor differences confuse children and they require a lot of help to*

Learners' confusion about the curricular switching happens at different levels, depending on how long they have been doing ZIMSEC. A learner who was doing ZIMSEC longer is likely to be more confused because he/she is used to localised information. A geography teacher gave an example of a student who experienced learning through ZIMSEC longer than the

*One student joined the school from Zimbabwe a few months before writing Cambridge examinations. He did not do well in the geography examination although he had all the notes that he got from his teachers in Zimbabwe. He did not know that he was supposed to have a broader view since it was going*

Another teacher challenged the view that learners with a long experience of ZIMSEC are likely to find it more difficult at Chitate Street School. The teacher argued that ZIMSEC is more challenging than Cambridge. Hence, a child who did ZIMSEC longer is likely to find Cambridge easier as long as he understands contextual differences, which exist between the two curricula. In some instances, it was noted that major curricula differences, which children

Refugee children experienced a slight change of content when they changed curriculum from ZIMSEC to Cambridge. There are some minor differences, which exist between ZIMSEC and Cambridge curricula in terms of content. There are some topics that are in ZIMSEC but not in the Cambridge curriculum. Sometimes both curricula may have a common topic, but the

*A challenge that Zimbabwean children had is that when they first see a topic that the teacher was going to teach, they think that it will be easy and it contains everything that they were doing in their country. Some children may say that they had already covered the topics and may not take the lesson seriously because they had the background. But, when I did a revision with them, they began to wonder and ask where some of the unfamiliar information was coming from. An example of this is, children used to work out only word equations in the ZIMSEC syllabus, but they are required to work out both word and chemical equations in Cambridge. That confuses learners. They wonder where some unfamiliar topics*

*fully understand the Cambridge curriculum.*

142 Immigration and Development

Cambridge curriculum. The teacher said:

*to be Cambridge he was going to sit for.*

were experiencing, were as a result of the content.

*<IP_ADDRESS>. Learners' experiences of curricula content*

depth of content would be different.

*and concepts were emerging from.*

A science teacher said:

*I find it difficult to understand the topics which we have to go into greater detail with. Sometimes we would think that we exhausted the question in a test, but we score low. Teachers guide us to provide more details and international examples.*

Teachers observed that Zimbabwean learners were sometimes failing to score higher in tests. This was not because they were not studying hard, but they misunderstood the Cambridge syllabus. One teacher said:

*At first, learners from Zimbabwe struggled with the Cambridge because they thought it was exactly the same as ZIMSEC which they were familiar with. But, as time lapsed, they began to understand the slight differences which exist. Despite the fact that learners know that there are slight differences between the two curricula, some of them still made some errors of writing examples which apply to the ZIMSEC.*

The Cambridge curriculum is very challenging to learners. One learner said: "I find the Zimbabwean curriculum easier than the Cambridge. It is not easy to adjust to the Cambridge, but I am coping because we have Zimbabwean teachers. We understand their English and they understand us very well".

Zimbabwean learners encountered subject content, which was different from what they were familiar with in their home country. In the Religious Studies subject, a learner explained content differences: "I used to do synoptic gospels at school (Gospels of Matthew, Mark and Luke) during Bible knowledge studies. But here, the curriculum allows us to do only one gospel (Gospel according to Luke) and Acts of the Apostles". The Bible knowledge teacher similarly argues that children from Zimbabwe are faced with the challenge of doing a new book of the Bible (Acts of the Apostles). They find it challenging because they were used to only doing synoptic gospels.

Learners were acquainted with the ZIMSEC curriculum, which offered a variety of subjects including practicals. They showed a great desire for practical subjects, which are not offered at a refugee school in South Africa. One learner said: "We do not have practical subjects (in our current curriculum) which we used to do back home. These subjects include technical graphics, woodwork, metalwork, fashion and fabrics, food and nutrition and building studies". Another learner said: "The school does not offer technical graphics which I was very good at in Zimbabwe. I do not have any practical subject which I am doing at the moment except computers".

#### *<IP_ADDRESS>. Learners' conceptual experiences of the curricula*

Teachers unanimously pointed out that the ZIMSEC and Cambridge curricula have conceptual differences, which make it difficult for children to understand. The two curricula treat similar concepts differently. For example, a history teacher said:

*The conceptualisation of Stone Age and Iron Age in ZIMSEC and Cambridge curricula is different. Learners used to understand Stone Age and Iron Age from an African point of view which is not the same as a Western perspective in the Cambridge. Similarly, children were acquainted with the topic of empires from the Afrocentric perspective in the ZIMSEC. Afrocentric empires in the ZIMSEC are arranged in a way that the King would be at the top, chiefs would be underneath and sub-chiefs at the bottom. Although the Eurocentric empireship is arranged hierarchically (like African), it has completely different concepts from the Afrocentric. Empireship in Europe is arranged in such a way that an Emperor would be at the top. Underneath, there would be lords and knights would be at the bottom.*

Children find it challenging to understand the Eurocentric approach, which is different from the Afrocentric approach. The switch of curricula has impacted on children's learning. Learners find their experience of curriculum switching confusing. They are confused by some minor differences, which exist between ZIMSEC and Cambridge. A form four learner who has been at Chitate Street School for two terms said:

*Some of the Cambridge information is very confusing. It is difficult to remember what principle to apply which is needed by Cambridge. We may end up confusing Cambridge and ZIMSEC. Sometimes I fail tests not because I did not study hard, but I get confused by the ZIMSEC and Cambridge concepts.*

## **4. Discussion**

The content, contextual and conceptual differences, which refugee children experienced at Chitate Street School form part of the microsystem in the Social Ecological Model. The microsystem entails a developing child interacting with proximal settings including the school and curricula [23]. Refugee learners interacted with teachers on a different subject matter and with the entire environment. This resonates with Schubert's conceptualisation of curriculum as the continuous interaction among the four common places: teachers, learners, subject matter and the milieu [24]. Interaction of refugee children with the people in their surroundings is inevitable during curriculum transition. Children will consult different school stakeholders about content of the new curriculum.

Content is considered a central concern in curriculum transition [1]. It is selected in terms of the readiness and interest level of the learners [25]. Pinar et al. looked at curriculum content as learning experiences, which have to be meticulously selected in order to attain stipulated objectives [2]. The content of the curriculum at a refugee school in South Africa was meticulously selected by parents, teachers and the community. When parents, teachers and the community decide a curriculum for children to learn, this forms the mesosystem, which, according to Bronfenbrenner, occurs when there is an interaction of microsystems between parents and teachers [15].

The involvement of a community in deciding a curriculum to adopt at a refugee school is a fundamental component of an exosystem in the Social Ecological Model. When a community makes decisions, which directly or indirectly impact on the education of refugee children, that would form an exosystem [26]. Although a community might not have direct communication with school children, its influence is greatly felt all the times [13].

The way in which the curriculum decision was made by the school and refugee community resonates with the ideas of Marsh and Willis who state that there are two focal points around which decisions about curricula can be made [27]. The first focal point is the nature of society. The curriculum takes into consideration the nature of the society so that it covers them in order to make students learn more about what is happening in their environments. The second focal point around which decisions about curricula can be made is the question raised by Marsh and Willis of whether the curriculum caters for the needs and interests of individual learners [27]. Cambridge was pointed out as the right curriculum for children because of potential benefits that it had for every learner. The curriculum is comprehensive in terms of its content, aims and objectives, and assessment standards [28].

The view of the principal of Chitate Street School that Cambridge was chosen because the Zimbabwean population, which constituted the dominant group was in favour of it, concurs with literature. The school curriculum at any one time reflects the values of the dominant group in society and thus tends to serve this group while marginalising the others [29]. The Cambridge curriculum was supported mainly because at the schools' inception, it had only Zimbabwean learners and teachers. The curricular transition which was experienced by Zimbabwean learners forms the macrosystem in the Bronfenbrenner's model. The macrosystem is formed by the way children experienced a change of curricula at the national level from ZIMSEC offered in Zimbabwe to the Cambridge, which is used at a refugee school in South Africa. The time period during which refugee children arrived in the host country and began to negotiate a new curriculum is an element of the chronosystem. The chronosystem among refugee children occurs when they are in the host country and encountering new educational experiences [26].

## **5. Conclusion**

*The conceptualisation of Stone Age and Iron Age in ZIMSEC and Cambridge curricula is different. Learners used to understand Stone Age and Iron Age from an African point of view which is not the same as a Western perspective in the Cambridge. Similarly, children were acquainted with the topic of empires from the Afrocentric perspective in the ZIMSEC. Afrocentric empires in the ZIMSEC are arranged in a way that the King would be at the top, chiefs would be underneath and sub-chiefs at the bottom. Although the Eurocentric empireship is arranged hierarchically (like African), it has completely different concepts from the Afrocentric. Empireship in Europe is arranged in such a way that an Emperor would be at the top. Underneath, there would be lords and knights would be at the bottom.*

Children find it challenging to understand the Eurocentric approach, which is different from the Afrocentric approach. The switch of curricula has impacted on children's learning. Learners find their experience of curriculum switching confusing. They are confused by some minor differences, which exist between ZIMSEC and Cambridge. A form four learner who

*Some of the Cambridge information is very confusing. It is difficult to remember what principle to apply which is needed by Cambridge. We may end up confusing Cambridge and ZIMSEC. Sometimes I fail tests not because I did not study hard, but I get confused by the ZIMSEC and Cambridge concepts.*

The content, contextual and conceptual differences, which refugee children experienced at Chitate Street School form part of the microsystem in the Social Ecological Model. The microsystem entails a developing child interacting with proximal settings including the school and curricula [23]. Refugee learners interacted with teachers on a different subject matter and with the entire environment. This resonates with Schubert's conceptualisation of curriculum as the continuous interaction among the four common places: teachers, learners, subject matter and the milieu [24]. Interaction of refugee children with the people in their surroundings is inevitable during curriculum transition. Children will consult different school stakeholders about

Content is considered a central concern in curriculum transition [1]. It is selected in terms of the readiness and interest level of the learners [25]. Pinar et al. looked at curriculum content as learning experiences, which have to be meticulously selected in order to attain stipulated objectives [2]. The content of the curriculum at a refugee school in South Africa was meticulously selected by parents, teachers and the community. When parents, teachers and the community decide a curriculum for children to learn, this forms the mesosystem, which, according to Bronfenbrenner, occurs when there is an interaction of microsystems between

The involvement of a community in deciding a curriculum to adopt at a refugee school is a fundamental component of an exosystem in the Social Ecological Model. When a community makes decisions, which directly or indirectly impact on the education of refugee children, that would form an exosystem [26]. Although a community might not have direct communication

with school children, its influence is greatly felt all the times [13].

has been at Chitate Street School for two terms said:

**4. Discussion**

144 Immigration and Development

content of the new curriculum.

parents and teachers [15].

Refugee children seldom triumph in African schools. This is not because they are not diligent but they lack basic support to ensure smooth curricular transition in the host country. There is a strong need for schools to support refugee children [10]. This constitutes inclusive education. Providing education to refugee children without giving them necessary support, which is needed for them to adapt to a new curriculum, is tantamount to setting them up for a failure.

## **Author details**

Lawrence Meda

Address all correspondence to<EMAIL_ADDRESS>
Cape Peninsula University of Technology, South Africa

## **References**

[15] Bronfenbrenner U. The Ecology of Human Development. Cambridge: Harvard University Press; 1979

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[3] Pinar WF. Farewell and celebrate. In: Pinar WF, editor. Contemporary Curriculum Discourses: Twenty Years of JCT. New York: Peter Lang Publishing; 2004. pp. xi-xx [4] Grumet MR.Autobiography and reconceptualization. In: Pinar WF, editor. Contemporary Curriculum Discourses: Twenty Years of JCT. New York: Peter Lang Publishing; 2004.

[5] Grumet M. The curriculum: What are the basics and are we teaching them? In: Kinchoe JL, Steinberg SR, editors. Thirteen Questions: Reframing Education's Conversation. New York:

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[8] Block K, Cross S, Riggs E, Gibbs L. Supporting schools to create an inclusive environment for refugee students. International Journal of Inclusive Education. 2014;**18**(12):

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[12] Nembaware L. The comparability of standards set at the Zimbabwe general certificate of education ordinary level in geography 2248 and integrated science 5006 over a period of three years. [Doctoral thesis]. Unpublished. Harare: University of Zimbabwe; 2004 [13] Bronfenbrenner U. Ecological models of human development. In: Gauvain M, Cole M, editors. Readings on the Development of Children. New York: Freeman; 1994. pp. 37-43

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## *Edited by Tiago Neves Sequeira*

This book deals with several issues linking immigration and social development. Following several approaches, from economic to sociological ones, it covers the many effects of the rising phenomenon of immigration. It deals with the effects of immigration on economic growth, on human capital accumulation, and on the government budget. Moreover, it also includes contributions on the social integration of immigrants and on the effects they have in some different cities. It covers studies in countries such as Norway, the USA, Romania, and South Africa. The book *Immigration and Development* is an essential reading for those who want to get a social sciences multidisciplinary approach to immigration as a social phenomenon.

Photo by lifehouseimage / iStock

Immigration and Development

Immigration

and Development

*Edited by Tiago Neves Sequeira*


*Article* **Comparing 2D and 3D Solar Radiation Modeling in Urban Areas**

**Štefan Koleˇcanský \*, Jaroslav Hofierka , Jozef Bogl'arský and Jozef Šupinský**

Institute of Geography, Faculty of Science, Pavol Jozef Šafárik University in Košice, Šrobárova 2, 04154 Košice, Slovakia<EMAIL_ADDRESS>(J.H<EMAIL_ADDRESS>(J.B<EMAIL_ADDRESS>(J.Š.)

**\*** Correspondence<EMAIL_ADDRESS>Tel.: +421-55-234-2352

**Abstract:** The use of solar radiation in the urban environment is becoming increasingly important for the sustainable development of cities and human societies. Several factors influence the distribution of solar radiation in urban areas, including urban morphology and the physical properties of urban materials. Most of these factors can be modeled with a relatively high accuracy using 2D and 3D solar radiation models. In this paper, the r.sun and v.sun solar radiation models are used to calculate solar radiation for the city of Košice in Eastern Slovakia to assess the accuracy of both approaches for vertical surfaces frequently found in urban areas. The results were validated by pyranometer measurements. The results showed relatively good estimates by the 3D v.sun model and poor estimates by the 2D r.sun model. This can be attributed to an improper representation of vertical surfaces by a digital surface model, which has a strong impact on solar resource assessments. We found that 3D city models prepared in level of detail 2 (LoD2) are not always adequate in case of complex buildings with morphological structures, such as terraces. These cast shadows on facades especially when solar altitude is high and, thus, assessments, even by a 3D model, are inaccurate.

**Keywords:** 3D city model; renewable energy; solar radiation; urban solar radiation model