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Human–robot interaction has extended its application horizon to simplify how human beings interact with each other through a remotely controlled telepresence robot. The fast growth of communication technologies such as 4G and 5G has elevated the potential to establish stable audio–video-data transmission. However, human–robot physical interactions are still challenging regarding maneuverability, controllability, stability, drive layout, and autonomy. Hence, this paper presents a systematic design and control approach based on the customer’s needs and expectations of telepresence mobile robots for social interactions. A system model and controller design are developed using the Lagrangian method and linear quadratic regulator, respectively, for different scenarios such as flat surface, inclined surface, and yaw (steering). The robot system is capable of traveling uphill (30\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{\circ }$$\end{document}∘) and has a variable height (600–1200 mm). The robot is advantageous in developing countries to fill the skill gaps as well as for sharing knowledge and expertise using a virtual and mobile physical presence. Electronic supplementary material The online version of this article (10.1007/s12369-020-00676-3) contains supplementary material, which is available to authorized users.

Which of the two climate change adaptation strategies – adjusting or improving farming (defined as Stepping Up) versus reducing or exiting farming (defined as Stepping Out) – provides better developmental outcomes for smallholder farmers? Are the drivers of these two strategies different? Do the outcomes and drivers vary according to farmland holding size? We investigated these unanswered questions, inspired primarily by a widespread but unverified suggestion that stepping out of farming can be a better option for smallholders. We utilised recent survey data from over eight hundred smallholder households located in climatic hazard-prone areas in Bangladesh. We applied a holistic Driver-Strategy-Outcome analytical framework and rigorous statistical methods, including index-based data aggregation, and Structural Equation Modelling with ‘mediation’ and ‘moderation’ analyses. Contrary to widespread speculations, we found that Stepping Out had a large negative effect on smallholders’ livelihood Outcomes; while Stepping Up had a moderate, but positive effect. The natural-environmental Drivers of Stepping Up and Stepping Out were similar; however, the psychological-institutional Drivers of each differed, with the same factor acting as a driver for one strategy whilst as a deterrent for the other. We found significant ‘mediatory’ effects of both the adaptation Strategies on Outcomes as well as significant ‘moderation’ effects of farmland holding size on the Drivers and Outcomes, with the positive effect of Stepping Up observed for smallholders owing lands of

Classification of samples into one or more populations is one of the main objectives of gene expression data (GED) analysis. Many machine learning algorithms were employed in several studies to perform this task. However, these studies did not consider the outliers problem. GEDs are often contaminated by outliers due to several steps involve in the data generating process from hybridization of DNA samples to image analysis. Most of the algorithms produce higher false positives and lower accuracies in presence of outliers, particularly for lower number of replicates in the biological conditions. Therefore, in this paper, a comprehensive study has been carried out among five popular machine learning algorithms (SVM, RF, Naïve Bayes, k-NN and LDA) using both simulated and real gene expression datasets, in absence and presence of outliers. Three different rates of outliers (5%, 10% and 50%) and six performance indices (TPR, FPR, TNR, FNR, FDR and AUC) were considered to investigate the performance of five machine learning algorithms. Both simulated and real GED analysis results revealed that SVM produced comparatively better performance than the other four algorithms (RF, Naïve Bayes, k-NN and LDA) for both small-and-large sample sizes. J. bio-sci. 28: 69-80, 2020

Background Ischemic heart disease (IHD) is a major cause of death globally. Countries vary in their rates, and changes have occurred over time. Nowadays, developing countries pose new public health challenges. Objectives The objective of the present study was to appraise the alterations in the levels of serum Zn, Cu, Fe, and Mn that occur in patients with ischemic heart disease and to depict the correlations of the effects of these changes that lead to the pathogenesis of IHD. Methods Zn, Cu, Fe, and Mn in the IHD patients were determined by Atomic Absorption Spectroscopy (AAS). Results This study evaluated 52 patients with IHD, and 61 healthy volunteers served as controls. The primary outcomes of interest were explored regarding the correlations of the serum levels of these trace elements in patients with IHD. The secondary outcomes were explored in terms of inter-element relations to connect them with the pathogenesis of IHD. Our study found significantly reduced levels of Zn and Cu (2.50 ± 0.19 mg/L and 2.52 ± 0.17 mg/L, respectively) and an elevated level of Fe (148.97 ± 17.25 mg/L) in the patient group with IHD. The level of Mn (7.32 ± 1.23 mg/L) was elevated in the sera of the patients with ischemic heart disease (IHD) compared to healthy control subjects. Conclusion Our results indicate strong associations of the pathogenesis of IHD with depleted serum levels of Zn and Cu and elevated Fe and Mn levels, which may provide a prognostic tool for the treatment of this concerning the disease., Cardiology; Biochemistry; Molecular biology; Pathophysiology; Public health; Pharmacology; Clinical research; Ischemic heart disease, Case-control study, Trace elements, Pearson's correlation, Bangladesh.

Progressive importance, swelling investment, and mounting national and global competition necessitate evaluation of the service quality of higher education. Quantifiable indicators such as student teacher ratio, student number, women participation, establishing new departments, and increase in the number of universities are no longer enough unless the student’s stand point is considered. This research probed the service quality of higher education in a public university in southern Bangladesh utilizing modified SERVQUAL gap model. The t-test results suggest that there is a significant service gap in all the selected service dimensions such as learning, teaching, recognition, assessment system, internet and library facilities, campus life, and non-academic administration. The results also mirror that little more than half (54.1%) students are satisfied with the service quality of the selected university and almost similar proportion (52.1 %) of the students have future interest in studying in the same university. Regression analysis reveals that learning and recognition are two important determinants of client’s overall satisfaction with the service of selected university. Importance Performance Analysis (IPA) advocates that the university should take immediate step in improving internet and library facilities, campus life, and non-academic administration. Factor analysis output confirms that slight modification of the proposed seven set model into six set factors can be employed by the management as off-the-rack service quality measurement tool. Key words: service quality, higher education, SERVQUAL, Bangladesh.

This article proposed a novel miniaturized design of coplanar wave guide (CPW) fed ultra wide band (UWB) tapered slot Vivaldi antenna for microwave imaging applications. Broken line exponential tapered profile and different types of slots have been incorporated in order to obtain the better performance and miniaturized antenna. All the important performance parameters of the proposed antenna such as return loss, BW, gain, directivity, VSWR, axial ratio, front to back ratio, accepted power, radiated power, surface current, radiation efficiency have been analyzed and enhanced up to the acceptable level. Finally, from the simulated validation, it is noticed that the proposed antenna would be a potential candidate for microwave imaging applications.

A slotted patch rectangular microstrip patch antenna (RMPA) has been designed and observed the effect of slotted patch in this paper. The slotted patch and photonic band gap (PBG) substrate increase the gain, bandwidth as well as efficiency of the proposed antenna which resonates at 2.4 GHz. In the proposed antenna, Glass (pyrex) (lossy) substrate is used having dielectric constant of 4.82 and tangent loss of 0.0054. All data of the characteristic parameters have been estimated by using computer simulation technology (CST) microwave studio (MWS) suite of version 2017. The bandwidth of the proposed antenna is of 174.3 MHz which covers entire ISM band (2 GHz – 2.49GHz). It possesses F/B ratio of 10.74 dB, return loss of −20.116 dB and efficiency of 68.79% at center operating frequency.

This paper presents a wearable planar printed meandering monopole textile antenna design having operating frequency of 2.4 – 2.45 GHz on 3 flexible substrate materials: Jeans, Leather and Cordura®. The printed elements have been designed by using a mender line technique to reduce the size of the antenna significantly than the proposed antennas of past literature. Antenna performance is analyzed for different bending conditions and Specific Absorption Rate (SAR) is evaluated when the antenna is in contact with human body using CST Microwave Studio. The compact design and miniature size of the antenna is suitable for easy integration in smart clothing for tracking, healthcare, security and other ISM applications.

A high gain optically transparent microstrip patch antenna for K band (18 GHz–27 GHz) satellite communication has been proposed and investigated in this paper. In order to make sure the property of optical transparency of the antenna, optically transparent materials have been chosen for all the layers of the microstrip patch antenna. Indium Tin Oxide (ITO) film is opted for the radiating patch and ground plane where the substrate is made of pyrex glass (lossy) (Ɛ r = 4.82 and tanδ = 0.0054). The proposed transparent antenna operates at center frequency of 24.8 GHz ranging from 17.625 GHz to 30.523 GHz that covers the entire K band of satellite communication. The transparency property of the patch antenna is useful to minimize the shadowing effect of the solar antenna as well as helpful to guarantee the maximum uses of satellite surface area. The proposed antenna has high IEEE gain of 12.36 dB and directivity of 13.38 dBi including efficiency of 92.38%. It also possesses very wide bandwidth (12.898 GHz), high front to back ratio (16.699 dB) and very good VSWR (1.0566) at center operating frequency.

A wideband inset feed microstrip Yagi-Uda array antenna on photonic crystal substrate with high gain and front to back (F/B) ratio for 5 GHz Wi-Fi band has been proposed. At first, a microstrip Yagi-Uda array antenna has been designed on Rogers RT/Duroid 5880 (lossy) having dielectric constant of 2.2 and tangent loss of 0.0009. Later on, few numbers of cylindrical air gaps has been introduced in the substrate and the length and width of patch somewhat has been readjusted without changing overall size of the antenna. In that case the performance of the antenna is enhanced in terms of IEEE gain (9.816 dB), directivity (10.15 dBi), bandwidth (396.2 MHz), efficiency (96.71%) and F/B ratio (29.094 dB) though return loss somewhat decreases. So the proposed antenna possesses very high front to back ratio as well as high gain and wide bandwidth. A vivid comparison between the microstrip Yagi-Uda array antennas without air gaps and with air gaps have also been presented in this paper.

This work demonstrates the impact of human body on an 800 MHz inset fed rectangular microstrip patch antenna characteristics. The antenna was simulated over a human phantom model consisting human thigh muscle using CST Microwave Studio. The distance between the antenna and human thigh muscle was varied to analyze the changes in antenna performance for waveguide port feeding. The results exhibited significant changes in antenna characteristics, especially the shifting of center frequency to a lower value due to the human body. Specific Absorption Rate (SAR) was studied as well to illustrate how on-body communication or mobile phone antennas of GSM band might affect human body when mobile phones are kept in pants pocket.

Purpose: Globally, many extension professionals and policy-makers are advocating fee based services, in addressing the fund shortage and sustainable provision of agricultural advisory services. Hence, the article attempts to expose the farmers' willingness to pay (WTP) as agricultural extension in Bangladesh is experiencing chronic fund crisis.Methodology: This study used contingent valuation method (CVM) for investigating farmers' WTP. Logit and Tobit model was employed to assess the determinants of WTP and amount willing to pay (AWTP) respectively. Besides, different qualitative methods were employed to have a deeper understanding of the research problems.Findings: WTP was conditioned by providing quality extension services at farm and/or home of the farmers. The study also focused on farmers preferred mode of payment, criteria influencing payment decisions and the type of services for which they are willing to pay. Paid model can contribute to quality extension services, if started with a marke...

Exposure of the general public to low-level RF fields causes direct or indirect coupling of the fields in the human body. Due to this coupling, there is an induction of the fields inside the body tissue that causes currents in the tissue while the tissue absorbs RF power. In this work, the RF absorption by a biological tissue was measured by using an antenna trainer in a laboratory set up by varying distances and angles of RF radiation source. Using the detector current, the absorbed power by the tissue as well as the incident component of Electric field upon the receiving antenna was calculated with and without the tissue. From calculating rms value of the field, the voltage inside the tissue was estimated. Using the absorbed power and voltage inside the tissue, the impedance inside the tissue was calculated. Results indicated that the more impedance values inside the tissue incur more absorption of RF power. The more dominant effects for angles than the distances were obtained for absorbed power by the tissue.

In this work, the impact of human heart on an 800 MHz inset fed rectangular microstrip patch antenna characteristics were investigated using CST Microwave Studio. The antenna was simulated over a mimic human heart muscle and the distance between them was varied to analyze the changes in Specific Absorption Rate (SAR) upon antenna performance parameters (specifically, directivity & surface current) for discreet and waveguide port feeding. The results exhibited that the center frequency of the antenna was shifted to lower value and an increase in SAR values when the antenna was closer to heart for both the feeding techniques. However, the discrete port had more values of SAR than the waveguide port but for both cases SAR decreased with the increment of antenna distance from heart. SAR values for up to 4 mm distance in between the antenna and human heart did not satisfy IEEE and ICNIRP standards. For increasing surface current, the SAR values decreases due to less penetration of flux inside the tissue for both feeding techniques. Increasing directivity resulted decrement of SAR values due to the fact that more reflection of the wave from the tissue happened for more directivity. This work demonstrates how mobile phone antennas of GSM band affect human heart and how human heart affects antenna resonance frequency when mobile phones are kept in chest pocket.

Vertically stacked pruned optical banyan networks with extra planes (in short, EP-VSOB networks) have lower switch count and optimal time complexity (O(log2 N)) for routing N input requests. However, blocking probability is relatively higher than that of a VSOB networks using regular banyan planes. In the EP-VSOB architecture, the number of pruned planes has always been considered as N , and a few extra planes (regular banyan) have been added with these pruned planes. In this paper we present the results of blocking analysis of a more generalized architecture in which the number of pruned planes can be 2x, where x ⩾ 0 in addition to the variable extra planes. This generalization helps us make a compromise between different constraints and performance metrics. Our simulation results show that for some given performance requirements (e.g. cost, speed or blocking probability) we can choose a network that has lower switch count compared to N -plane pruned crosstalk-free optical banyan networks. For example, to ensure blocking probability

In this paper, 15 different shaped (E, F, inverted F, G, H, I, L, inverted L, S, T, inverted T, U, inverted U, W and inverted W) conventional microstrip patch antennas along with a dumbbell (H) shaped Defected Ground Structure (DGS) in each are designed and simulated at 2.4 GHz operating frequency using CST Microwave Studio Suite. The efficiency of microstrip patch antennas are compared in terms of surface wave concept and the antenna with H shaped patch exhibiting total efficiency of −2.546 dB is found most efficient. The implementation of this work is highly anticipated to be employed for designing hybrid shaped patches for WLAN, wireless network (Wi-Fi and Bluetooth), nonstandard RF remote, ISM band applications.

In this paper, we address the issue of faster connection establishment in a large vertically stacked optical Banyan (VSOB) network. The best known global routing algorithm, which turns an N × N crosstalk-free VSOB network into a rearrangeably non-blocking one, has time complexity O ( N log N ). This is quite large compared to O ( N log N ) time complexity of a single plane banyan network, which is a self-routing network with very high blocking probability. For a large size of switching network this O ( N log N ) time complexity may result unacceptably long delay. Therefore, an optical network with very low blocking probability and O ( N log N ) time complexity will be useful. Previously proposed Plane Fixed Routing (PFR) algorithm has O (log N ) time complexity but results in higher than 2% blocking probability with zero-crosstalk constraint for a network as large as 4096 × 4096 at full load. In this paper, first we propose the pruning of VSOB networks that reduces the hardware cost by almost 30%. The networks can still use the PFR algorithm and results in the same blocking probability. However, we show that the blocking probability can be reduced dramatically while keeping the optimum time complexity O (log N ) by allowing only a small amount of crosstalk. Then, we propose a new kind of switching networks in which extra regular banyan planes have been added with the pruned VBOS (P-VSOB) networks. Necessary routing algorithms, namely, PFR_RS and PFR_LS show that this new switching network can reduce the blocking probability to very low value even with zero-crosstalk constraint while keeping the hardware cost 3almost the same as for P-VSOB networks. Both these algorithms also have time complexity O ( N log N ).

Vertical stacking of multiple optical banyan networks is a novel scheme for building banyan-based nonblocking optical switches. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves the properties of small depth and absolutely loss uniformity but loses the nice self-routing capability of banyan networks. To guarantee a high switching speed, routing in VSOB network needs special attentions so that paths can be established as fast as possible. The best known global routing algorithm for an N × N nonblocking VSOB network has the time complexity of O(Nlog N), which will introduce an unacceptable long delay in path establishment for a large size optical switch. In this paper, we propose two fast routing algorithms for the VSOB network based on the idea of inputs grouping. The two algorithms, namely plane fixed routing (PFR) algorithm and partially random routing (PRR) algorithm, have the time complexities of O(log N) and O$(\sqrt{N})$ respectively, and FR algorithm can actually turn a VSOB network into a self-routing one. Extensive simulation based on a network simulator indicates that for large VSOB networks our new algorithms can achieve a reasonably low blocking probability while guarantee a very high switching speed.

Banyan networks are attractive for constructing directional coupler (DC)-based optical switching networks for their small depth and self-routing capability. Crosstalk between optical signals passing through the same DC is an intrinsic drawback in DC-based optical networks. Vertical stacking of multiple copies of an optical banyan network is a novel scheme for building nonblocking (crosstalk-free) optical switching networks. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves all the properties of the banyan network, but increases the hardware cost significantly. Though much work has been done for determining the minimum number of stacked copies (planes) required for a nonblocking VSOB network, little is known on analyzing the blocking probabilities of VSOB networks that do not meet the nonblocking condition (i.e., with fewer stacked copies than required by the nonblocking condition). In this paper, we analyze the blocking probabilities of VSOB networks and develop their upper and lower bounds with respect to the number of planes in the networks. These bounds depict accurately the overall blocking behaviors of VSOB networks and agree with the conditions of strictly nonblocking and rearrangeably nonblocking VSOB networks respectively. Extensive simulation on a network simulator with both random routing and packing strategy has shown that the blocking probabilities of both strategies fall nicely within our bounds, and the blocking probability of packing strategy actually matches the lower bound. The proposed bounds are significant because they reveal the inherent relationships between blocking probability and network hardware cost in terms of the number of planes, and provide network developers a quantitative guidance to trade blocking probability for hardware cost. In particular, our bounds provide network designers an effective tool to estimate the minimum and maximum blocking probabilities of VSOB networks in which different routing strategies may be applied. An interesting conclusion drawn from our work that has practical applications is that the hardware cost of a VSOB network can be reduced dramatically if a predictable and almost negligible nonzero blocking probability is allowed.

With the current technology, all-optical networks require nonblocking switch architectures for building optical cross-connects. The crossbar switch has been widely used for building an optical cross-connect due to its simple routing algorithm and short path setup time. It is known that the crossbar suffers from huge signal loss and crosstalk. The Clos network uses a crossbar as building block and reduces switch complexity, but it does not significantly reduce signal loss and crosstalk. Although the Spanke's network eliminates the crosstalk problem, it increases the number of switching elements required considerably (to 2N 2 - 2N). In this paper, we propose a new architecture for building nonblocking optical switching networks that has much lower signal loss and crosstalk than the crossbar without increasing switch complexity. Using this architecture we can build non-squared nonblocking networks that can be used as building block for the Clos network. The resulting Clos network will then have not only lower signal loss and crosstalk but also a lower switch complexity.

During the path establishment, states of switching elements in the switch network may need rearrangement. C.-T. Lea et. al [1] has first mentioned about the rearrangement behavior of the switching networks. He has analyzed the frequency of its occurrence using stochastic method. It is notable that rearrangement behavior of switching network includes rearrangement of connections and rearrangement of switching elements. Optimization of rearrangement cost of switching network can save both power and time, which in turn can increase the switching speed. This paper determines the rearrangement cost of strictly non-blocking Vertically Stacked Optical Banyan networks in terms of switching elements. We believe that our result will be helpful in designing, implementing and analyzing different algorithms of the networks.

Optical banyan networks can be made rearrangeably nonblocking using its multiple copies in unison. Such rearrangeably nonblocking networks are known as vertically stacked optical banyan (VSOB) networks. Centralized control routing algorithm for this rearrangeably nonblocking optical banyan networks has time complexity O ( N log2 N ). A distributed control routing algorithm with time complexity O (log2 N ) has been proposed recently in which authors have considered N completely connected processors to take routing decision which practically would be very difficult to implement for large N . In this paper we propose two distributed control routing algorithms where processors are loosely connected. In the first algorithm ) ( N O processors work in pipelined fashion, and take the routing decision in linear time. In the second algorithm N inputs synchronously hunt for a free route among ) ( N O copies of a banyan network using a look up table. This algorithm has time complexity ) ( N O . Also the processors do not need to be completely connected, which makes it more practical for implementation.

Due to its nice properties of small depth and absolute signal loss uniformity, vertical stacking of optical banyan (VSOB) networks becomes an attractive optical switch architecture. It is expected that a VSOB switch will have a good fault-tolerant capability, because it consists of multiple banyan networks. To verify our expectation, in this paper we study the overall blocking behavior of a VSOB switch by establishing an upper bound on its blocking probability in presence of link failures. The upper bound accurately depicts the overall blocking behavior of a VSOB switch for a reasonable small link failure rate, as verified by extensive simulation results. Although our upper bound demonstrates that VSOB switches have a good fault-tolerance property, it reveals a surprising overall blocking behavior of a faulty VSOB switch that, not as we usually expected, the blocking probability of the switch may not always increase monotonously with the increase of link failure rate. Our upper bound is significant, because it provides switch designers a quantitative tool to determine the effects of link failure on the blocking behavior and to estimate the maximum blocking probability of a VSOB switch, in which different routing algorithms can be applied with a guaranteed performance in terms of blocking probability and hardware cost.