Impact of Relay Cooperation on the Performance of Large-scale Multipair Two-way Relay Networks

We consider a multipair two-way relay communication network, where pairs of user devices exchange information via a relay system. The communication between users employs time division duplex, with all users transmitting simultaneously to relays in one time slot and relays sending the processed information to all users in the next time slot. The relay system consists of a large number of single antenna units that can form groups. Within each group, relays exchange channel state information (CSI), signals received in the uplink and signals intended for downlink transmission. On the other hand, per-group CSI and uplink/downlink signals (data) are not exchanged between groups, which perform the data processing completely independently. Assuming that the groups perform zero-forcing in both uplink and downlink, we derive a lower bound for the ergodic sumrate of the described system as a function of the relay group size. By close observation of this lower bound, it is concluded that the sumrate is essentially independent of group size when the group size is much larger than the number of user pairs. This indicates that a very large group of cooperating relays can be substituted by a number of smaller groups, without incurring any significant performance reduction. Moreover, this result implies that relay cooperation is more efficient (in terms of resources spent on cooperation) when several smaller relay groups are used in contrast to a single, large group.Comment: Accepted to Globecom 2018. Copyright 2018 IEE

Study and analysis of motion artifacts for ambulatory electroencephalography

Motion artifacts contribute complexity in acquiring clean electroencephalography (EEG) data. It is one of the major challenges for ambulatory EEG. The performance of mobile health monitoring, neurological disorders diagnosis and surgeries can be significantly improved by reducing the motion artifacts. Although different papers have proposed various novel approaches for removing motion artifacts, the datasets used to validate those algorithms are questionable. In this paper, a unique EEG dataset was presented where ten different activities were performed. No such previous EEG recordings using EMOTIV EEG headset are available in research history that explicitly mentioned and considered a number of daily activities that induced motion artifacts in EEG recordings. Quantitative study shows that in comparison to correlation coefficient, the coherence analysis depicted a better similarity measure between motion artifacts and motion sensor data. Motion artifacts were characterized with very low frequency which overlapped with the Delta rhythm of the EEG. Also, a general wavelet transform based approach was presented to remove motion artifacts. Further experiment and analysis with more similarity metrics and longer recording duration for each activity is required to finalize the characteristics of motion artifacts and henceforth reliably identify and subsequently remove the motion artifacts in the contaminated EEG recordings

Laser-assisted high speed machining of aluminium alloy: The effect of ultrasonic induced droplet vegetable-based cutting fluid on surface roughness and tool wear

Laser-assisted high speed milling is a subtractive machining method that employs a laser beam to thermally soften material's surface in order to enhance machinability at high material removal rate with improved surface finish and tool life. Ultrasonic-assisted milling is an advanced manufacturing technology where ultrasonic source is connected with cutting tool, that has demonstrated effectiveness in terms of acquiring good surface topography and high surface finish. Despite this, its application is limited at low speed and is not widely applied for high volume production. Here, an ultrasonic-induced droplet delivery method is employed as an efficient method for laser-assisted high speed milling operation. In this study the effect of ultrasonic-induced droplet cutting fluid on surface roughness and flank wear of 6082 aluminium alloy is experimentally investigated using response surface methodology (RSM) and the results are compared with the conventional droplet cutting fluid. The ultrasonic creates acoustic streaming, acoustic cavitation as well as cavitation bubbles in the cutting fluid. This acoustic energy is able to increase the local temperature of cutting fluid with which the laser power combinedly softens the machined surface, thereby reducing the tool abrasion and surface roughness. The results show a favourable reduction in surface roughness and flank wear by 11.04 and 1.37%, respectively, in comparison to conventional droplet cutting fluid. Clearly, the laser-assisted high speed milling with ultrasonic-induced droplet cutting fluid will be applicable in high production rate manufacturing where it will yield less production time, low operating cost and, at the same time, give better surface finish and longer tool life. © 2021 Old City Publishing. All rights reserved

Extreme Learning Machine in Laser-Assisted Machining Using Waste Palm Cooking Oil

Use of lubricating/cutting fluids is crucial in machining processes to reduce friction, alleviate heat accumulation and prolong tool life. To minimize environmental and health impacts, a number of studies using vegetable oil-based cutting fluid have been investigated and reported demonstrating similar performance obtained using commercial cutting fluids. However, massive use of vegetable oil for such purposes would undeniably trigger issues of food security. In order to mitigate food waste, the primary objective of the chapter is to demonstrate the application of waste palm cooking oil as a potential lubricating fluid in laser-assisted machining of metal. By considering kinematic and dynamic viscosities of the waste cooking oil, its effects on surface roughness and tool wear are studied by predicting using extreme learning machine (ELM). The prediction results show that the average errors are only 0.51% and 1.19% for surface roughness and flank wear, respectively, suggesting good agreement between observation and prediction

Numerical simulation on wind-driven cross ventilation in square arrays of urban buildings with different opening positions

Effective wind-driven cross ventilation requires a well-designed opening, such as a window, to allow sufficient exchange between indoor and outdoor air, especially when the building is surrounded by other buildings. Using computational fluid dynamics, the present study investigated the effect of different opening positions on wind-driven ventilation in a building in an area with a packing density of 25%. The renormalization group κ-ε turbulence model, a type of Reynolds-averaged Navier-Stokes (RANS) model, was used to characterize the airflow in cubical building blocks arranged in a square array. Nine different configurations of aligned cross openings and nine configurations with non-aligned outlet positions were tested. The ventilation rates obtained for the aligned cross openings showed that openings positioned at the uppermost of the windward and leeward façade provided highest ventilation rate. The ventilation rate was reduced by 75% when the openings were positioned at the bottom of the façade. As for the fixed inlet in the centre, the ventilation rate was 100% higher when the outlet is at the top of the leeward façade compared to the bottom of the façade. The outcomes of this study show that opening position is imperative in providing effective wind-driven cross ventilation in urban areas

Laser-Assisted High Speed Machining of 316 Stainless Steel: The Effect of Water-Soluble Sago Starch Based Cutting Fluid on Surface Roughness and Tool Wear

Laser-assisted high speed milling is a subtractive machining method that employs a laser to thermally soften a difficult-to-cut material’s surface in order to enhance machinability at a high material removal rate with improved surface finish and tool life. However, this machining with high speed leads to high friction between workpiece and tool, and can result in high temperatures, impairing the surface quality. Use of conventional cutting fluid may not effectively control the heat generation. Besides, vegetable-based cutting fluids are invariably a major source of food insecurity of edible oils which is traditionally used as a staple food in many countries. Thus, the primary objective of this study is to experimentally investigate the effects of water-soluble sago starch-based cutting fluid on surface roughness and tool’s flank wear using response surface methodology (RSM) while machining of 316 stainless steel. In order to observe the comparison, the experiments with same machining parameters are conducted with conventional cutting fluid. The prepared water-soluble sago starch based cutting fluid showed excellent cooling and lubricating performance. Therefore, in comparison to the machining using conventional cutting fluid, a decrease of 48.23% in surface roughness and 38.41% in flank wear were noted using presented approach. Furthermore, using the extreme learning machine (ELM), the obtained data is modeled to predict surface roughness and flank wear and showed good agreement between observations and predictions

Cellular and Cytokine Responses to Salmonella enterica Serotype Typhi Proteins in Patients with Typhoid Fever in Bangladesh

We assessed interferon-gamma (IFN-γ) responses via enzyme-linked immunosorbent spot (ELISPOT) to a number of S. Typhi antigens in samples from humans with S. Typhi bacteremia and typhoid fever in Bangladesh. Compared with responses in healthy endemic zone controls, there were significantly increased IFN-γ responses at the time of clinical presentation (acute phase) and at convalescence 14–28 days later. The majority (80–90%) of IFN-γ expressing T cells were CD4+. We observed a significant increase in interleukin-17 (IL-17) positive CD4 + T cells at convalescent versus acute stage of infection using an intracellular cytokine staining assay. We also found that stimulated peripheral blood mononuclear cells (PBMCs) produced significantly increased levels of a number of cytokines at the convalescent versus acute phase of infection, including IFN-γ, MIP-1β, sCD40L, TNF-β, IL-13, and IL-9. These results suggest that S. Typhi antigens induce a predominantly Th1 response, but that elevations in other cytokines may be modulatory

Evaluation of the role of perceived quality and satisfaction of beneficiaries about the health care services and benefits of community clinics in Bangladesh

Introduction Bangladesh provides free healthcare to its citizens through 10,723 community clinics which provide one-stop healthcare services that is vital in ensuring primary healthcare. Measuring beneficiary' contentment is crucial to improve the quality of care and the perceived service quality have a significant impact on how often people use those health services. This study focuses on perceived quality and satisfaction of beneficiaries about the primary health care services and benefits of community clinics in Bangladesh. Methods A quantitative descriptive survey was conducted from March 2019 to April 2019 in the catchment area of 80 community clinics located at 16 Upazila under eight districts of eight divisions in Bangladesh. The survey compiled local data on client’s experience on health care service of community clinics. Besides, Sixteen Upazilas from eight districts were randomly selected for conducting interviews. Results Data was provided by a total of 760 female participants, among them majority (41%) belonged to the age group of 18-24 years old, and this very group showed more satisfaction than others (Odds Ratio 1.44). Besides, childless married women were also found to be content with the community clinic services compared to the remaining types of clients (Odds Ratio 1.64). However, gender, education, and economic perspective were positive aspects of getting service from community clinics. Conclusions Although there is a challenge balancing psychosocial and medical care, promoting client-oriented care with a focus on the cultural factors of the area is vital. This can be done through community-focused training together with explaining written prescriptions to the beneficiary, including the signs, symptoms, treatment, and referral points. The study findings will enable responsible authority to improve quality of primary health care services, realizing beneficiary’ ideas of community clinic service quality

CMOS-based cryogenic control of silicon quantum circuits

The most promising quantum algorithms require quantum processors hosting millions of quantum bits when targeting practical applications. A major challenge towards large-scale quantum computation is the interconnect complexity. In current solid-state qubit implementations, a major bottleneck appears between the quantum chip in a dilution refrigerator and the room temperature electronics. Advanced lithography supports the fabrication of both CMOS control electronics and qubits in silicon. When the electronics are designed to operate at cryogenic temperatures, it can ultimately be integrated with the qubits on the same die or package, overcoming the wiring bottleneck. Here we report a cryogenic CMOS control chip operating at 3K, which outputs tailored microwave bursts to drive silicon quantum bits cooled to 20mK. We first benchmark the control chip and find electrical performance consistent with 99.99% fidelity qubit operations, assuming ideal qubits. Next, we use it to coherently control actual silicon spin qubits and find that the cryogenic control chip achieves the same fidelity as commercial instruments. Furthermore, we highlight the extensive capabilities of the control chip by programming a number of benchmarking protocols as well as the Deutsch-Josza algorithm on a two-qubit quantum processor. These results open up the path towards a fully integrated, scalable silicon-based quantum computer

Psychological impact of COVID-19 on healthcare workers: cross-sectional analyses from 14 countries

Abstract Background Healthcare workers (HCWs) have been impacted psychologically due to their professional responsibilities over the prolonged era of the coronavirus disease 2019 (COVID-19) pandemic. The study aimed to identify the predictors of psychological distress, fear, and coping during the COVID-19 pandemic among HCWs. Methods A cross-sectional online survey was conducted among self-identified HCWs across 14 countries (12 from Asia and two from Africa). The Kessler Psychological Distress Scale, the Fear of COVID-19 Scale, and the Brief Resilient Coping Scale were used to assess the psychological distress, fear, and coping of HCWs, respectively. Results A total of 2447 HCWs participated; 36% were doctors, and 42% were nurses, with a mean age of 36 (±12) years, and 70% were females. Moderate to very-high psychological distress was prevalent in 67% of the HCWs; the lowest rate was reported in the United Arab Emirates (1%) and the highest in Indonesia (16%). The prevalence of high levels of fear was 20%; the lowest rate was reported in Libya (9%) and the highest in Egypt (32%). The prevalence of medium-to-high resilient coping was 63%; the lowest rate was reported in Libya (28%) and the highest in Syria (76%). Conclusion COVID-19 has augmented the psychological distress among HCWs. Factors identified in this study should be considered in managing the wellbeing of HCWs, who had been serving as the frontline drivers in managing the crisis successfully across all participating countries. Furthermore, interventions to address their psychological distress should be considered