Channel Estimation for Massive MIMO Systems

In MIMO millimeter-wave (mmWave) systems, while the hybrid digital/analog precoding structure provides the ability to increase the reach rate, it also faces the challenge of reducing the channel time limit due to the large number of horns on both sides of the Tx / Rx. . In this paper, channel measurement is done by searching with multiple beams, and a new hierarchical multi-beam search system is proposed, using a pre-designed analog codebook. Performance tests show that, compared to a highperformance system, the proposed system not only achieves a high level of success in getting multiple beams under normal system settings but also significantly reduces channel estimation time Keywords: Massive MIMO, Channel Estimation, precoding

Investigation of Unsteady Pressure Pulsation in New Type Dishwasher Pump with Special Double Tongue Volute

Through numerical simulations, this work analyzes the unsteady pressure pulsation characteristics in new type of dishwasher pump with double tongue volute and single tongue volute, under volute static and rotation conditions. Likewise, the performance tests were also carried out to verify the numerical results. Multiple monitoring points were set at the various positions of new type dishwasher pump to collect the pressure pulsation signals, and the relevant frequency signals were obtained via Fast Fourier Transform, to analyze the influence of volute tongue and its passive speed on the pump performance. The results reveal that when the double tongue volute is stationary, the pressure pulsation amplitudes increase from the impeller inlet to the impeller outlet. Under the influence of shedding vortex, the pressure pulsation in the lateral region of tongue becomes disorganized, and the main frequency of pressure pulsation changes from blade frequency to shaft frequency. In addition, compared with the static volute, double tongue volute can effectively guide the water flow out of the tongue during the rotation process, thus ensuring good periodicity for pressure pulsation in the tongue region. Accordingly, a volute reference scheme with passive rotation speed is proposed in this study, which can effectively improve the pressure pulsation at tongue position, and provides a new idea for rotor-stator interference to guide the innovation of dishwasher.

The Multi Split Ventilator System: Performance Testing of Respiratory Support Shared by Multiple Patients

Ventilator sharing has been proposed as a method of increasing ventilator capacity during instances of critical shortage. We sought to assess the ability of a regulated, shared ventilator system (Multi Split Ventilator System, MSVS) to individualize support to multiple simulated patients using one ventilator. We employed simulated patients of varying size, compliance, minute ventilation requirement, and PEEP requirement. Performance tests were performed to assess the ability of the QSVS, versus control, to achieve individualized respiratory goals to clinically disparate patients sharing a single ventilator following ARDSNet guidelines. Resilience tests measured the effects of simulated adverse events occurring to one patient on another patient sharing a single ventilator. The QSVS met individual oxygenation and ventilation requirements for multiple simulated patients with a tolerance similar to a single ventilator. Abrupt endotracheal tube occlusion or extubation occurring to one patient resulted in modest, clinically tolerable changes in ventilation parameters for the remaining patients. The QSVS is a regulated, shared ventilator system capable of individualizing ventilatory support to clinically dissimilar simulated patients. It is also resilient to common adverse events. The QSVS represents a feasible option to ventilate multiple patients during a severe ventilator shortage.

Development and Performance Measurement of an Affordable Unmanned Surface Vehicle (USV)

Indonesia is a maritime country that has vast coastal resources and biodiversity. To support the Indonesian maritime program, a topography mapping tool is needed. The ideal topography mapping tool is the Unmanned Surface Vehicle (USV). This paper proposes the design, manufacture, and development of an affordable autonomous USV. The USV which is composed of thruster and rudder is quite complicated to build. This study employs rudderless and double thrusters as the main actuators. PID compensator is utilized as the feedback control for the autonomous USV. Energy consumption is measured when the USV is in autonomous mode. The Dynamics model of USV was implemented to study the roll stability of the proposed USV. Open-source Mission Planner software was selected as the Ground Control Station (GCS) software. Performance tests were carried out by providing the USV with an autonomous mission to follow a specific trajectory. The results showed that the developed USV was able to complete autonomous mission with relatively small errors, making it suitable for underwater topography mapping.

The comparative analysis of Java frameworks: Spring Boot, Micronaut and Quarkus

The aim of the work is a comparative analysis of three frameworks designed for building web applications for the Java programming language: Spring Boot 2.4.4, Micronaut 2.5.4 and Quarkus 1.13.4.Final. Test applications were prepared, equipped with the same functionality as used in the experiment consisting in measuring the server response times to a POST request – performing the data entry into the database. For each test application, the scenario aimed at measuring the time of handling requests under various load conditions was repeated five times. During each repetition of the scenario, the load which was the average number of requests sent per second by virtual users was increased. In parallel with performance tests, the reliability of the test applications was measured. Reliability was defined as the percentage of requests sent to the server that ended in a failure. The comparative analysis also took into consideration the volume of the code of the test applications based on the selected frameworks. The performed analyses showed that in terms of all the criteria considered in this work Micronaut proved to be the best framework.

Performance comparison of programming interfaces on the example of REST API, GraphQL and gRPC

The article presents a comparison of the performance of three ways of implementing programming interfaces used in web applications - REST, GraphQL and gRPC. For the purposes of the research, three applications were developed, which were made in each of the indicated technologies and with the same functionalities. The applications were used for performance tests carried out with the use of the k6 tool. The applications are used to measure the execution time, performance and volume of processed data during display and adding operations. The obtained results allowed for the conclusion that the best interface in terms of performance (measured as the number of transactions per second) and server response time is REST. However, in terms of the smallest data volume, gRPC is the best choice.

Modifikasi dan uji performansi mesin perontok lada dengan mekanisme perontok silinder berjaring

Pepper is one of Indonesia's leading agricultural products. However, post-harvest handling of pepper, such as the threshing process, is still done traditionally. Efforts to overcome these problems done by developing a mechanical threshing process, including by designing and construction a mesh thresher cylinder type of pepper threshing. Test results show, this pepper thresher has a weakness, namely low threshing efficiency so that it needs to developed. Based on these conditions, research is needed that aims to develop, modify and done performance tests on the pepper thresher. The modification was made by making the contact angle between the thresher cylinder and the threshing net is 60o and resulted length of the threshing contact field of about 5.23 cm. The independent variable was the thresher cylinder rotational speed varied into 540, 471, 451 and 352 rpm. The dependent variables were capacity, threshing efficiency and percentage pepper of damage. The results of the analysis showed that the rotational speed of the threshing mechanism had a very significant effect on the capacity, threshing efficiency and the percentage pepper of damage. Increasing the speed of the thresher cylinder can increase the capacity and percentage of damaged pepper, but reduce threshing efficiency. The threshing efficiency increase of the pepper thresher before and after modification was from 35.8% to 95.93% on the approaching treatment.

Designing and Constructing Skill Performance Tests for Futsal Female Players

The research aimed at designing and constructing a number of tests for skill performance endurance for female futsal players as well as identifying standard criteria for these tests. The researcher used the descriptive method on (105) female futsal players from the northern region of Iraq including clubs (Tenahi, Fetat Arbil, Shekhan, Jehan, Gaz Al Shemal, Afrodate, Serwan, Newi). The data was concluded and treated using SPSS to concluded (6 – 8) criteria for these tests under study.

Internet of Things (IoT) Cloud Platform Using MQTT End-to-Cloud Architecture

IoT devices are constrained in computation and storage, therefore cannot store all long-term obtained data or perform complex computations. Shifting those jobs to cloud platform are feasible, yet rising heterogeneity and security issues. This study proposes an IoT cloud platform to facilitate communication among heterogeneous devices and the cloud while ensuring devices’ validity. It uses publish/subscribe paradigm with an end-to-cloud architecture and HTTP-based auth server. The proposed system has successfully addressed heterogeneity and security issues. Performance tests conclude that the fewer publishers publish data simultaneously, the smaller the delay. Moreover, the system performs better at up to 250 publishers as the average delay is under 1000 ms, compared to 500 publishers that has average delay above 1000 ms. On its scalability, in 250-concurrent-publishers experiment, the system affords 191 publishers responded in under one second with 100% success rate. In 500-concurrent-publishers one, 187 responded in under one second with 99% rate.

Associations of Urinary Collagen II Neoepitope C2C with Total Knee Replacement Outcomes: Is OA a Systemic Disease in Rapidly Progressive Cases?

The objective of this study was to investigate the dynamics of the urinary collagen type II C-terminal cleavage neoepitope (uC2C) before and after total knee replacement (TKR) in rapid knee OA progressors. C2C in the urine was measured by IBEX-uC2C assay in 86 patients (mean age: 59.9 years) with symptomatic knee OA (kOA) undergoing TKR, assessed before surgery and 3 and 12 months after. The patients’ condition was determined by self-assessment questionnaires, by lower limb performance tests, and by radiography. In the preoperative period, the uC2C level was significantly higher in females than in males, and was associated with the radiographic severity of kOA. A weak correlation between the C2C and knee pain was observed in the whole group and in males, but not in females. The individual dynamics of uC2C after TKR were heterogenic. In general, uC2C increased three months after TKR, but fell to the preoperative level after 12 months. A higher preoperative uC2C implied the tendency to diminish as a result of TKR, and vice versa. TKR did not stop the degradation of Coll2 in the tissues in the majority of cases. The pre-TKR uC2C predicts the postoperative uC2C level. The uC2C dynamic seems to be sex-specific, so it could be considered a prospective pre- and post-TKR biomarker for progressive kOA.