**4.4 Haptic vests and jackets**

Originally designed for medical investigation, Physician Mark Ombrellaro developed a haptic vest that enabled the wearer to feel the impact of bullets, explosions and/or even hand taps in the trunk of the player's body. The 3RD Space Vest is commercialized by TN Games and is advertised as the only gaming peripheral device that allows you to feel what your game character feels. It works with pressured air to provide the player pressure and impact forces that can emulate a wide scope of direction and magnitude (TN Games, 2011).

Others have worked on similar systems, and although they have not focused on the application in games specifically, it is clear how such technologies could also be applied in a game scenario. In the University of Ottawa in Canada, Jongeun Cha and others have worked in a device to enhance teleconferencing. They developed a jacket that enhances communication with the physical and emotional connection by allowing participants give encouraging pats to one another (Cha et al, 2009). Similarly, researchers at the National University of Singapore developed the Huggy Pajama wearable system, where the remote communication between parent and child is enabled through virtual hugs. This is possible by using a doll with embedded pressure sensors as input device and a haptic jacket as the actuator for the hug at the other end. The hug is reproduced by air pockets and the experience is further enhanced by adding a heating element to the device to mimic the warmth of a hug (Teh et al, 2008).


2. Mathematical modelling

This section presents background on mathematical modelling of infectious diseases. Mathematical modelling is a useful tool to understand complex phenomena including disease transmission dynamics and their control strategies. There are several types of modelling that are generally used: deterministic, stochastic, statistical, agent-based modelling, and the others. A deterministic model is mostly used because it is easily solved and can include many parameters or variables. The model is in the form of system of differential equations.

Many mathematical models have been developed to investigate disease transmission dynamics including vector-borne diseases [14]. The model is based on a standard SIR model where the human population is divided into susceptible (S), infected (I), and recovered (R) [15]. The susceptible individuals become exposed after being contacted with infected individuals at a rate β. They then recover at a rate γ. The model is written in the following system of differential equations:

$$\frac{dS}{dt} = -\beta \frac{SI}{N}, \quad \frac{dI}{dt} = \beta \frac{SI}{N} - \gamma I, \quad \frac{dR}{dt} = \gamma I. \tag{1}$$

The model can then be extended to include other compartments and parameters depending on the characteristics of diseases. For example, if the disease has long incubation period, we can add exposed compartment. If the disease is transmitted via vector, we can add another system of equations describing vector dynamics. When one aims to investigate the effects of vaccination, vaccinated compartment can be included. The important principles in modelling are to know characteristics of studied phenomena and the purpose of the research. The principles have been applied when we formulate mathematical models for Wolbachia-carrying mosquito population dynamics and dengue with Wolbachia.


**Yutaro Iwamoto, Naoaki Hashimoto and Yen-Wei Chen \***

College of Information Science and Engineering, Ritsumeikan University, Shiga 525-8577, Japan<EMAIL_ADDRESS>(Y.I<EMAIL_ADDRESS>(N.H.)

**\*** Correspondence<EMAIL_ADDRESS>
Received: 16 December 2019; Accepted: 4 February 2020; Published: 9 February 2020

**Abstract:** This study proposes real-time haze removal from a single image using normalised pixel-wise dark-channel prior (DCP). DCP assumes that at least one RGB colour channel within most local patches in a haze-free image has a low-intensity value. Since the spatial resolution of the transmission map depends on the patch size and it loses the detailed structure with large patch sizes, original work refines the transmission map using an image-matting technique. However, it requires high computational cost and is not adequate for real-time application. To solve these problems, we use normalised pixel-wise haze estimation without losing the detailed structure of the transmission map. This study also proposes robust atmospheric-light estimation using a coarse-to-fine search strategy and down-sampled haze estimation for acceleration. Experiments with actual and simulated haze images showed that the proposed method achieves real-time results of visually and quantitatively acceptable quality compared with other conventional methods of haze removal.

**Keywords:** haze removal; dark channel; atmospheric-light estimation; coarse-to-fine search strategy


**8. References**

[14] Kong LQ, Bi QL, Niu MY, Zhu SY, Yang J, Liu WM. Journal of the European Ceramic Society 2013; 33: 51-59.

128 Tribology in Engineering

**Author details**

*of Sciences, Lanzhou, PR China*

**Acknowledgement**

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*State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy*

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**Chapter 8**

© 2013 Shahabuddin et al., licensee InTech. This is an open access chapter 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.

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.

© 2013 Shahabuddin et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons

**Development of Eco-Friendly Biodegradable**

Various types of lubricants are available all over the world including mineral oils, synthetic oils, re-refined oils, and vegetable oils. Most of the lubricants which are available in the market are based on mineral oil derived from petroleum oil which are not adaptable with the environment because of its toxicity and non-biodegradability [1, 2]. Unknown petroleum reserve and the increasing consumption, which made concern to use petroleum based lubricant thus, to find the alternative lubricant to meet the future demand is an important issue [3]. Therefore, vegetable oil can be played a vital role to substitute the petroleum lubricant as it possesses numerous advantage over base lubricant like renewability, environmentally friendly, biodegradability, less toxicity and so on [4-8]. It has been reported that yearly 12 million tons of lubricants waste are released to the environment [9]. However, it is very difficult to dispose it safely for the mineral oil based lubricants due its toxic and non-biodegradable nature. To reduce the dependency on petroleum fuel, legislations have been passed to use certain percentage of biofuel in many countries, such initiative also required for lubricant as well [10]. Vegetable oils are mainly triglycerides which contain three hydroxyl groups and long chain unsaturated free fatty acids attached at the hydroxyl group by ester linkages acids favors triglycerides crystallization [11, 12]. The unsaturated free fatty acid which is defined as the ratio and position of carbon-carbon double bond, one two and three double bonds of carbon chain is named as a oleic, linoleic, and linolenic fatty acid components respectively [13]. The main limitations of vegetable oil are its poor low temperature behavior, oxidation and thermal stability and gumming effect [14, 15]. These stabilities and pour point behavior can be ameliorated by transesterification. Moreover the inferior flow property does not affect much in the tropical countries. Quinchia et al. [16] stated that, improving the potentiality of biolubricants some technical properties including available range of viscosities are need to improved. To do so, environmentally friendly viscosity modifier can be used. viscosity is the most important property for the lubricants

**Biolubricant Based on Jatropha Oil**

M. Shahabuddin, H.H. Masjuki and M.A. Kalam

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/51376

**1. Introduction**


**4. Conclusions**

OCTA is a very promising image technique that is continually improving and offers numerous advantages over FA in DR management. Many clinical studies indicate their usefulness in early diagnosis, follow-up, identification of prognostic factors, and treatment of DR and related complications. Nevertheless, OCTA is a relatively new technique and the usefulness of most of the quantitative data it allows to obtain needs to be investigated. Finally, it would be important to have greater interchangeability between data offered by different software and improve image quality by reducing artifacts.

*Optic Coherence Tomography Angiography in Diabetic Retinopathy DOI: http://dx.doi.org/10.5772/intechopen.108077*


**2. Limitations of the conventional technology**

## **2.1. Basic limitations**

*Real-time"* is a more meaningful definition in such cases where the image is seen to be live, while the velocity ratio (i.e. the speed of the target to that of sound) is significant, or forming

On the other hand, *"Determinism"* can be an important concept in defining a key aspect of image integrity. This can be a predominant requirement – for example in quantitative image analysis where accurate spatial information is important. The use of the term "determinism" in this context does not really mean "as it happens" (although the time interval between a moving target and its presentation as an image is usually small). Determinism essentially means that the spatial integrity of a moving target is persevered in the image to a high degree. In the case of ultrasound the theoretical limit of spatial determinism can only be reached if a single ultrasound pulse emitted by an imaging device produces a complete image field of the object within its time of flight. This is clearly not achievable with the existing line-serial imaging technology, but it is one of the main features of the new hybrid imaging system described later

In late 1980's, the techniques for generating 3-D images from a collection of 2-D images have been demonstrated [4]. Producing a single frame of such an image may have taken about 20 minutes then, but with the advancement of computing power and processing techniques, live 3-D and 4-D volume imaging reaching pseudo-real time volumes of surface features have now

One of the fairly recent additions to B-mode imaging is the so called Zone-sonography [6]. A main feature in this system is the acquisition of data from a relatively low number of zone sectors, as opposed to line-by-line acquisition, thereby significantly improving the temporal artefacts inherent with the conventional methods. It has been claimed that in some cases, this approach could produce speed improvements of up to 10 times compared to conventional lineserial imaging systems [6], although the zones in themselves are produced using serial

In addition, in the case of medical imaging, various echo enhancement techniques such as Coded Excitation (CE) and Digitally Encoded Ultrasound (DEU) which improve sensitivity, penetration and contrast are now been widely used [7, 8]. CE is a pulse compression technique which is designed to differentiate and boost weak return signals from deep within the body. This is done by transmitting an encoded pulse sequence, isolating the coded return signal and amplifying only this signal, while regaining longitudinal resolution which is distributed within the insonifying pulse train [7]. Some systems using CE can also show blood flow together with the body tissue as a B-mode image, without the need for overlay as would be the case with Doppler imaging. Tissue Harmonic Imaging (THI) is another widely used technique which reduces haze, clutter and image artefacts. In this approach, higher harmonic components of the echoes generated by the tissues due to non-linear propagation are used

an image frame takes significant time.

272 Advancements and Breakthroughs in Ultrasound Imaging

in this chapter.

scanning.

**1.3. State-of-the-art techniques**

come into existence [4, 5].

instead of the fundamental [9].

A fundamental limitation with all of the above existing technology, which arises from the need for line-serial scanning, is the loss of temporal resolution. Attempts to improve this aspect by increasing computing power alone cannot give the full-potential of real-time imaging and may only give improvements with largely diminishing returns.

The second limitation, for example when using linear-array technology, is the use of smaller effective aperture compared to the size of the total array aperture, hence affecting the lateral resolution achievable. These two limitations are analysed below in order to reveal the extent to which they affect potential performance in ultrasonic imaging. Although the discussion is based on using linear arrays for clarity, the same considerations are valid for other configu‐ rations.

Figure 1 below shows a linear array transducer coupled to a test medium. The test object is assumed to be homogeneous and have a depth (d). The array consists of (N) elements with a total aperture size (A). The elements are usually switched on as a group (as shown) rather than single elements to improve lateral resolution, since this depends on the effective aperture, as depicted in equation 3. The next group in the firing sequence advance by only one element thus keeping the line resolution equal to the spacing of the array elements.

**Figure 1.** Line-serial scanning

Between individual scanning lines, a rest period (trest) is applied before firing the second consecutive group of elements as a practical requirement to allow multiple echoes to die down and time for acquisition, storage and display of data.

$$\begin{aligned} \mathbf{t}\_{\text{f}} &= \begin{pmatrix} \mathbf{N} \cdot \mathbf{N}\_{\text{G}} \end{pmatrix} \begin{bmatrix} \left(\frac{2\mathbf{d}}{\mathbf{c}}\right) & + & \mathbf{t}\_{\text{rest}} \end{bmatrix} \\\\ \text{1. } & \text{Frame rate} \quad \approx \quad \frac{1}{\mathbf{t}\_{\text{f}}} \end{aligned} \tag{2}$$

The other limitation with a linear array scanner, as mentioned above, is the degradation of lateral resolution arising from the size of the aperture formed by the group of elements firing at any instant of time. The lateral resolution is limited by the beam width of the transducer or the group of elements. The diffraction limited beam width for a given transducer of aperture

δθ = 1.22 λ

to that achievable with the fully available aperture is not realised.

**2.2. Ideal properties of an imaging system**

where, λ is the wavelength of sound in the medium. As can be clearly seen, for each scan line, D is determined by the number of elements within the group fired and this is clearly very much less than the total aperture size (A) of the array. Hence, the lateral resolution corresponding

From the above discussion, it is clearly evident that two key properties of an ideal real-time ultrasonic imaging system is that it should be able to produce a complete image frame of the object volume from one insonifying pulse, while utilizing the full aperture available for each frame of the image. Additionally, an ideal system should produce focused images of the whole object field at the same instant of time irrespective of the distances of targets from the surface (Isochronicity) while maintaining accurate object-to-image spatial resemblance (image linearity). It is also clear that the existing technology utilising line-serial scanning cannot achieve these ideal properties and therefore alternative techniques may be needed to improve speed and high resolution capabilities beyond that feasible with conventional technology. This requires investigating non-conventional imaging modalities that can possess those capabili‐ ties, and the ways of overcoming limitations that may have precluded their use in practice. The next section presents some early developments that have some of the above key properties achieved through direct ultrasonic image reconstruction. Beyond academic interest, these techniques have not realised in large-scale use except in very specific applications due to other

Direct ultrasonic image visualization using alternative methods, such as ultrasonic hologra‐ phy, Bragg diffraction imaging etc. have been documented by many researchers in the past [12, 13, 14]. One such technique that has the above ideal properties is the Direct Ultrasonic Visualization of Defects (DUVD) system demonstrated by Hansted in the 1970's [12]. As schematically shown in Figure 3(a), this is a passive acousto-optical configuration which uses a pair of ultrasonic lenses with a common focus to form an ultrasonic image of the object field in a transparent medium from echoes received from a test object; much in the same way as an

D (4)

http://dx.doi.org/10.5772/56378

275

Breaking Through the Speed Barrier — Advancements in High-Speed Imaging

(D) could be expressed as:

inherent problems.

**3. Non-conventional methods**

**3.1. Direct ultrasonic imaging**

With reference to Figure 1, time (tf ) taken to produce one frame is:

where, NG is the number of elements in the group firing at any one time and c is the speed of sound. Hence, as an example, when using an array with 150 elements, coupled to a medium in which the velocity of sound is 1.54 mm/μs, thickness 20 cm, NG = 50, and neglecting trest, it can be seen that the maximum frame-rate achievable is about 75. This will be even less when trest is applied.

However, the above frame rate may sound adequate, and indeed so for many cases, but the line-serial scanning introduces a basic limitation in the case of fast moving targets such as heart valves or machinery. During the scanning time within a frame, one part of the target may have displaced significantly relative to another, causing spatial distortion, thus a frozen image of the target at any time may differ significantly from its actual position or shape. This is illustrated in Figure 2.

**Figure 2.** Formation of temporal artefacts

With reference to Figure 2, spatial distortion (Δs) could be written as:

$$\Delta \mathbf{s}\_{\{\mathbf{x}\}} = \begin{array}{c} \mathbf{x} \\ \hline \mathbf{A} \end{array} \times \begin{array}{c} \mathbf{t}\_{\{\mathbf{f}\}} \times \begin{array}{c} \mathbf{v}\_{\mathbf{x}} \\ \end{array} \tag{3}$$

where, vX is the velocity of a point (x) on target.

The other limitation with a linear array scanner, as mentioned above, is the degradation of lateral resolution arising from the size of the aperture formed by the group of elements firing at any instant of time. The lateral resolution is limited by the beam width of the transducer or the group of elements. The diffraction limited beam width for a given transducer of aperture (D) could be expressed as:

$$
\delta\Theta = \begin{array}{c c}
\frac{1.22\ \lambda}{D} \\
\end{array}
\tag{4}
$$

where, λ is the wavelength of sound in the medium. As can be clearly seen, for each scan line, D is determined by the number of elements within the group fired and this is clearly very much less than the total aperture size (A) of the array. Hence, the lateral resolution corresponding to that achievable with the fully available aperture is not realised.

#### **2.2. Ideal properties of an imaging system**

( ) é ù æ ö = + ê ú ç ÷

c

f

where, NG is the number of elements in the group firing at any one time and c is the speed of sound. Hence, as an example, when using an array with 150 elements, coupled to a medium in which the velocity of sound is 1.54 mm/μs, thickness 20 cm, NG = 50, and neglecting trest, it can be seen that the maximum frame-rate achievable is about 75. This will be even less when

However, the above frame rate may sound adequate, and indeed so for many cases, but the line-serial scanning introduces a basic limitation in the case of fast moving targets such as heart valves or machinery. During the scanning time within a frame, one part of the target may have displaced significantly relative to another, causing spatial distortion, thus a frozen image of the target at any time may differ significantly from its actual position or shape. This is

A

x

( ) D = ´´ x f x x s t v

Vx

Δs

A (3)

Direction of Scan

V1

With reference to Figure 2, spatial distortion (Δs) could be written as:

t

f G rest

2d t N - N t

\ »

With reference to Figure 1, time (tf

274 Advancements and Breakthroughs in Ultrasound Imaging

trest is applied.

illustrated in Figure 2.

**Figure 2.** Formation of temporal artefacts

where, vX is the velocity of a point (x) on target.

1 Frame rate

ë û è ø

) taken to produce one frame is:

(2)

From the above discussion, it is clearly evident that two key properties of an ideal real-time ultrasonic imaging system is that it should be able to produce a complete image frame of the object volume from one insonifying pulse, while utilizing the full aperture available for each frame of the image. Additionally, an ideal system should produce focused images of the whole object field at the same instant of time irrespective of the distances of targets from the surface (Isochronicity) while maintaining accurate object-to-image spatial resemblance (image linearity). It is also clear that the existing technology utilising line-serial scanning cannot achieve these ideal properties and therefore alternative techniques may be needed to improve speed and high resolution capabilities beyond that feasible with conventional technology. This requires investigating non-conventional imaging modalities that can possess those capabili‐ ties, and the ways of overcoming limitations that may have precluded their use in practice. The next section presents some early developments that have some of the above key properties achieved through direct ultrasonic image reconstruction. Beyond academic interest, these techniques have not realised in large-scale use except in very specific applications due to other inherent problems.