Number Of Slots Research Articles

Research on Winding MMF Harmonics of the PMSM with the Same Number of Poles and Slots

Research on Winding MMF Harmonics of the PMSM with the Same Number of Poles and Slots

Концептуальная структура бинарной аксиологической оппозиции истина — ложь

Axiological categories and the concepts they consist of have always been a major area of interest in science. The development of cognitive linguistics has opened new perspectives for the study of axiological events, categories and concepts within them. This article explores the structure of the axiological binary opposition truth-lie, based on the material of the English language. In English, the verbalised concept truth encodes information about both objective truth as well as its subjective perception and re-translation. A combination of methods — definitional, frame and conceptual analyses — makes it possible to investigate and model the structure of the frames TRUTH and LIE, identify their main slots and the type of conceptual information they encode. The results of the analyses suggest that the two frames have the same structure and the same number and type of slots. However, the conceptual content of the slots is different. From the conceptual point of view, the axiological binary opposition truth — lie is a continuum having an intermediate blend zone “neither truth nor lie”, incorporating the axiological paradoxes, which form the conceptual basis of manipulation.

Numerical approach to improve UVC radiation for air disinfection and investigation of the scalability

This study simulates the inactivation of SARS-CoV-2 viruses by UVC radiation. A reference case is simulated with computational fluid dynamics, which is designed the same way as the experimental decentral air purifier test device to use valid boundary data. The UVC radiation sources are small LEDs. They are implemented on the inside faces of two penetrable baffles in the airway. The distance between the two baffles and the slots in the baffles will be altered. The number of open slots determines the flow structure in the light chamber. IF all slots are open the flow is straight through the chamber. In two other cases the flow is forming a vortex. The simulations have three goals: First, validate the CFD-model with experimental data. Second, maximizing the radiation on each simulated aerosol and reducing the pressure difference of the device. Third, is to show the scalability to larger HVAC devices. In this study a maximum UVC dose is reached with partly closed slots and short distance between the baffles. Generally, more slots reduce the pressure loss. Extending the light chamber increase the radiation dosage for straight flows, in the case of vortex flow the dosage decreases. The problem is scalable, the solution is only partly scalable.

Completion Time Minimization for Data Collection in a UAV-enabled IoT Network: A Deep Reinforcement Learning Approach

In this paper, we study the completion time minimization in an unmanned aerial vehicle (UAV)-enabled Internet of Things (IoT) network, where the UAV tries to collect all the data generated by the ground IoT devices for further processing. To simplify the analysis, the continuous time horizon is discretized into several time slots. The duration of each time slot is set to be less than the pre-defined threshold such that the UAV's location can be considered as unchanged during each time slot. In our work, we aim to minimize the completion time of the UAV by optimizing the association scheme of the IoT devices, the location (i.e., the trajectory) and velocity of the UAV at each time slot. However, the formulated problem is challenging to solve by traditional optimization methods considering the unknown number of time slots (which leads to the unknown number of decision variables) and non-convex functions. We thus reformulate it as a Markov decision process (MDP) and propose a deep deterministic policy gradient (DDPG)-based method to efficiently solve it. The DDPG-based algorithm uses deep function approximators instead of finding the action that maximizes the state-action value, and is therefore well suited to solve high-dimensional, continuous control problems. Extensive numerical results are presented to validate the effectiveness of our proposed algorithm.

Secure Transmission Over Multiple Access Wiretap Channel by Cross-Time Interference Injection

Due to the openness of wireless communication, information transmitted in the multiple access channel is vulnerable to eavesdropping by illegitimate users. Classic artificial noise-assisted schemes can improve security but are not suitable for power-constrained users. To address this problem, we propose a cross-time interference injection scheme in this paper, which improves security by introducing cross-time self-interference and inter-user interference, and does not require artificial noise. The proposed scheme exploits the properties of the Hadamard matrix and the wireless channels, so that the eavesdropping channel suffers from stronger interference than the legitimate channel. We analyze the security performance when both the legitimate receiver and the eavesdropper exploit the successive interference cancellation (SIC) scheme, including the secrecy sum rate, the secrecy capacity, and the secrecy outage probability. We further investigate the effect of the number of eavesdropper’s antennas, the number of legitimate users, and the number of time slots used by the scheme on the security performance, and obtain the corresponding relationship between these parameters when achieving a positive secrecy rate. Finally, simulation results corroborate our theoretical analysis.

A dokumentumfilm-tervek piaci követelményeiről és ezek átalakulásáról – első rész

The international market of the documentary projects – the so called “pitching forums” – was formed about 30 years ago at the International Documentary Forum Amsterdam (IDFA) film festival. There the commissioning editors of different documentary TV slots could pre-buy the films at the level of project. Many documentaries could be made thanks to those pre-buys. After a while, many similar financing forums were formed in different countries, connected to different festivals, and they continue to play an important role regarding the documentary productions, although, due to the decreasing number of the documentary TV slots, it is more and more difficult to get financing at such forums. But they started to play an important role in the distribution of the films. Those who are not promoting their film at the level of project, have difficulties in the distribution of the completed film. This study is based on the personal experience of the author, who as film director and producer participated at preparation classes for different pitching forums, so he could observe not only the development of his projects, but also of the projects of the other participants. This study is also about the formal requirements of the documentary film projects presented at such pitching forums.

Toward Optimal RFID Frame Lengths

In dense radio frequency identification (RFID) systems, reducing reading times is crucial. For tag anti-collision management, most RFID systems rely on Frame Slotted ALOHA (FSA). The most common method used to reduce the reading time for large tag populations is the optimization of the number of slots per frame. Each slot in real RFID systems has a different duration determined by its type (idle, successful, or colliding). Furthermore, by detecting the strongest transponder, colliding slots can be converted into successful slots, a phenomenon known as the capture effect. The strongest tag reply can also be intentionally detected by enhancing the reader’s capabilities with collision recovery. RFID readers may also be capable of identifying slot types using the physical layer and reducing the colliding slot time because in this case, the reader can immediately terminate the connection as there is no reason to reply with an invalid acknowledge and wait for the time-out. This paper presents an exhaustive analysis of the effect of slot type identification and capture probability on the frame length in the presence of different tag cardinality estimation techniques. Additionally, the effect of the new optimized frame length on the total reading time reduction is addressed with different tag encoding schemes. Theoretically, experimental results for FM0 encoding show that our technique achieves a total reading time reduction between 5.5% and 11.3% over methods that do not take into account slot type identification in the frame length optimization. For Miller encoding scheme with M=2,4, and 8 the reading time is decreased by 9%, 6%, and 1% respectively. The maximum reading time reductions are achieved at collision recovery probabilities values of 0.4 for FM0 and Miller with M=2 and 0.45 & 0.6 for M=4, and M=8, respectively. In case the reader does not have any collision recovery capability and the Shoute algorithm is used to estimate the tag cardinality, the maximum reading time reductions dropped to 3.9%, 2.6%, 1.7%, and 1.3% for FM0, Miller encoding scheme with M=2,4, and 8, respectively. However, if a more optimized tag cardinality estimation technique is used such as the Schoute algorithm, the maximum reading time reductions are 7.8%, 4.8%, 3.3%, and 2.4% for FM0, Miller encoding scheme with M=2,4 and 8, respectively.

International Service-Learning: Proposal for A Multi-Dimensional Model for Student Selection

In an age where students display competency in diverse fields of activities, selecting qualified candidates from an assorted group for a service-learning exchange program demands a multidimensional approach. The framework for student selection for International Service-Learning (ISL) at Union Christian College (UCC) has been designed bearing this in mind. Its value increases when there is a proportionally higher number of applicants for a limited number of slots. Practiced for the last three years (2018-2021), the model has been designed using seven-fold criteria. The compositely designed rubric examines Q&A responses, perspectives on SL, and problem solving skills at various stages in the assessment. Each assessment level is graded from A to D, with highest A and least D. The evaluation is conducted to assess student social commitment, community engagement, leadership qualities and personal initiatives. The process of enriching writing skills and designing SL activities for diverse communities during the SL committee selection process prepares students to meet challenges in the field. Students prepared under such a method are selected for ISL.

권선법에 따른 매입형 영구자석 전동기의 운전특성 분석 및 와전류 손실 저감에 관한 연구

Concentrated IPMSM has advantages in various aspects, such as space ratio, mass productivity, and copper loss, but concentrated winding has a limitation that the eddy current loss of permanent magnets is quite large compared to distributed winding. Eddy current loss means the heat of the rotor and becomes larger during high-speed operation. Therefore, in the concentrated IPMSM that requires high-speed operation, it is essential to design to reduce eddy current loss. In this paper, in order to reduce the eddy current loss of the IPMSM, a shape that increases the reluctance of the q-axis was applied to the rotor, and each was designed by dividing into concentrated winding and distributed winding. The number of pole slots of concentrated winding was selected as 6 poles and 9 slots, and the number of pole slots of distributed winding was selected as 6 poles and 27 slots. Through FEA, the voltammetry limit circle and T-N curve were compared according to each winding method. By comparing the d-axis inductance and q-axis inductance, a model that is advantageous at high speed was confirmed, and the no-load and load characteristics according to the operating speed were compared in detail.

Vehicle parking: A smart solution

The system proposed in this paper provides an effective solution in finding the vacant space and manages the vehicles entering in and out of parking area. The system consists of Arduino Uno, Liquid Crystal Display (LCD), Servo motor and Infrared (IR) Sensors. Two IR Sensors placed just before and after the entrance of the gate which detects the motion of the vehicle either entering or leaving the gate or slot area. The Arduino Uno, a microcontroller counts the number of available slots based on the entry or exit of the vehicle and the state of each slot i.e., either the slot is empty or full and provides a feedback which is displayed on the LCD. This whole process makes the system fully automated and thus provides a solution for vehicle parking in a smart way. The proposed automated system causes the driver to navigate in reaching to the vacant slot using display thus reduces search time. The proposed system can be implemented at places where heavy number of vehicles needs to be parked.

Protection by diversity in elastic optical networks subject to single link failure

Among the multipath protection schemes found in the literature, the Partitioning Dedicated Path Protection — PDPP proposes to divide the total transmission rate required by the connection in equal parts, and then proceed the transmission of each part using multiple disjoint paths. Nevertheless, it is also possible to partition the transmission rate unequally among paths, enabling benefits to network performance. This article proposes a mixed-integer linear programming (MILP) formulation to find an optimized unequally partitioning of connections’ transmission rate among multiple disjoint paths, in order to provide dedicated protection and reduction in maximum number of slots on network and average bandwidth squeezing. The solution is analysed over a number of realistic networks, showing that the proposed formulation significantly reduces the spectral usage compared to traditional protection mechanisms and reduces the amount of squeezing required compared to the former PDPP approach.

System Reliability Analysis for a Stochastic Liner Container Shipping Service with Stochastic Terminals

In the container shipping industry, a company could have an advantage over its competitors while its liner container shipping system (LCSS) can successfully transport the requested demand. However, some uncertainties such as unstable sea state, terrible weather, sailor’s negligence, and the condition of vessels would affect the number of slots on the vessel to place containers when shipping on different legs. Thus, that number should be regarded as stochastic. At the container terminal, containers are loaded from and unloaded to the vessel ship by the quay cranes. The number of available quay cranes at each terminal is also stochastic because of the reservation of other competitors. Therefore, this study proposes an algorithm that constructs an LCSS as a stochastic liner container shipping network (SLCSN) model to analyze the network reliability. Network reliability is defined as the probability that all vessels in the SLCSN can satisfy the demands within the time threshold. For an executive of the liner container shipping company, the network reliability can be utilized as the performance indicator to make an appropriate managerial decision.

Pulsating multiple nano-jet impingement cooling system design by using different nanofluids for photovoltaic (PV) thermal management

The present work proposes a new cooling system for thermal management and cooling of photovoltaic (PV) systems. Pulsating flow with multiple jet impingement is considered by using different fluid types. Hybrid nanofluid and alumina–water nanofluid having cylindrical ans spherical shaped nanoparticles are used as the cooling medium. The study is conducted by using finite volume method for various values of pulsating amplitude (between 0 and 1), Strouhal number (between 0.01 and 1), solid volume fraction of nanoparticles (between 0 and 2%) and slot number of the impinging jet (between 1 and 13). It is observed that pulsating amplitude is more effective on the cooling performance enhancement as compared to frequency while average Nusselt number (Nu) rises by about 63.5% while temperature drop of 2.16 °C can be achieved when pulsation amplitude is increased from 0 to 1. Nanofluid with cylindrical shaped nanoparticles and hybrid nanofluid show very similar trends while temperature drop of 2.6 °C is achieved when cooling system with nanofluid-cylinder in pulsating flow case is compared with pure-fluid in non-pulsating flow configuration. When nanoparticles loading amount on the thermal improvement is compared, the most favorable cases are obtained for nanofluid-cylinder and hybrid nanofluid case. The average Nu increments become 3.5%, 22.8% and 22.9% for nanofluid-spherical, nanofluid-cylinder and hybrid nanofluid when lowest and highest nanoparticle loading amount cases are compared. Increasing the slot number in pulsating flow case significantly rises the Nu and drops the average panel surface temperature. When different systems are compared pulsating nano-jets cooling system using alumina–water nanofluid with cylindrical shaped nanoparticles provides the most effective cooling system while while temperature drop of ΔT=37.30 °C is achieved at the highest amplitude and highest loading of nanoparticles in the pure fluid as compared to uncooled PV system.

Dispersion aware first random fit spectrum allocation approach in elastic optical network (EON)

Abstract Elastic Optical Network (EON) is gaining a lot of attention these days because of its capability to dynamically utilize the network resources. It is possible to alter data rates in accordance with the required application by adjusting a number of spectrum slots which enhances spectral efficiency. However, it is difficult for new requests to access the usage of spectrum resources during the entire process especially when the spectrum is split into a number of small segments. Another key challenge in EON is to achieve effective routing and spectrum allocation. This entails looking for a specified route and identifying contiguous aligned spectrum slots for allocation to various requests. In this way, EON aims maximizing the connection while using the least amount of available spectrum resources. With this in mind, this research developed a first random fit (FRF) spectrum allocation technique that takes into account dispersion, which is a major physical flaw in optical networks. This scheme includes the effect of dispersion for the spectrum allocation approach. Using a FRF approach, this scheme tends to allocate a greater number of connection requests and spectrum is utilized in more efficient way. Starting with the lowest indexed slot, this scheme uses the First Fit algorithm and the less stable modulation technique like BPSK to search for and assign the spectrum slot. A random fit assignment strategy is used with a more robust modulation technique (QPSK) to exploit the next higher indexed spectrum slot which suffers larger dispersion effect. Longer light path requests are assigned to lower indexed spectrum slot (lower dispersion slots) using BPSK modulation technique, while shorter light path requests are sent to next higher indexed spectrum slot (greater dispersion slots) using QPSK modulation technique capturing the dispersion sensitive technique. The results show that the proposed technique achieves a minimal bandwidth blocking probability (BBP) of 0.048, Eye opening Penalty (EOP) of 45.45 dB and Quality Factor of 3.889 and B.P compared with other First Fit (FF) and Random Fit (RF) spectrum allocation schemes.

Influence of key-slot structure on interior ballistic performance of low-velocity aircraft

To investigate the interior ballistic performance of the cooperation of the guide slot and the guide key at a low velocity, a pressure-structure coupling method was put forward to obtain the effect of different structures. A lumped parameter model of an interior ballistic was utilized to govern the propellant combustion. The mechanical behaviors were predicted based on the engineering software ABAQUS. We coupled the interior ballistic parameters and the structures through moving boundaries by using a user subroutine interface VUAMP in ABAQUS. The results show that the coupling approach can accurately predict the movement process of the aircraft in the barrel, and different numbers of slots and different guide key structures were simulated. The fewer the slots, the smaller the resistance of the aircraft, but the corresponding guiding performance is poor. Inversely, more slots lead to the better guiding performance. Furthermore, different guide key structures have a greater impact on the exit velocity of the aircraft, but have little effect on the guiding performance. The guide key with edge rounding-off in side is a better structure case, which can obtain a stable rotational velocity and high launch speed on the premise of ensuring rigidity. The result can be applied to provide an important reference in determining reasonable numbers of slots and guide key structures for the application in engineering.

Variation Regularity and Measurement of Zero-Sequence Inductance of Fractional Slot Concentrated Winding PMSMs

The zero-sequence inductance is a vital parameter for the performance analysis of permanent magnet machines, especially under faulty conditions or in open-winding machines. This paper focuses on the zero-sequence inductance calculation of fractional slot concentrated winding permanent magnet synchronous machines (FSCW-PMSMs), and reveals the variation regularity of this kind of inductance and its various components against pole/slot combinations, using the winding function and finite element methods. Moreover, based on the analysis of 36-slot FSCW-PMSMs with different pole numbers, the dependency of each inductance component on the pole/slot combination is discussed in detail. To validate the regularities, experimental measurements of zero-sequence inductance are implemented in the prototype of the 36-slot stator. It is found that the regularities are independent of specific slot or pole numbers, which provide guidelines for optimum pole/slot combination selection, to mitigate the problems caused by zero-sequence current.

Characteristics of Parking Lots Located along Main Roads in Terms of Cargo Truck Requirements: A Case Study of Poland

The issue related to parking lots has a multidimensional nature. For the purposes of the article, the analysis covered 113 parking lots located directly next to national roads in the Mazovian Voivodeship (Poland), which is similar in terms of economic development and conditions of the linear infrastructure to other countries in Central Europe. The conducted research included analyzing the correlation of parameters in individual parking lots and those related to nearby roads (traffic volume, technical quality) and the type of area in which they occurred (population density). In addition, the presented results describe the capacity of parking in the analyzed region in terms of the number of available parking slots for heavy goods vehicles, the size of the additional operating area, and the presence of security-related elements (fencing, lighting, physical protection, monitoring). The analysis demonstrated a correlation between some parameters (type of nearby road and security rs = 0.35, area size and number of slots rs = 0.35) and significant differences in results between private and public parking lots (average number of slots 18 versus 34, percent of most secured parkings 45% versus 69%). The obtained innovative results can be used by public institutions and entities providing parking services to reorganize the space at parking places and to conduct more effective analyses from the point of view of future investments in infrastructure accompanying the public road network.

Optimization Design of Pot Slot Structure of Tea De-enzyming and Carding Machine

The problems of the uneven strip shape and low efficiency of tea de-enzyming and carding machines in the working process were addressed by analyzing the trajectory of tea particles and establishing a force model diagram of tea particles in the pot slot. The three-dimensional geometric model of the tea de-enzyming and carding machine was drawn using UG software, and the simulation model of tea particles was established using EDEM software. The work efficiency of the tea de-enzyming and carding machine was improved, and the rate of broken tea was reduced using the EDEM software to simulate the movement of tea particles in the pot slot under different heights of the convex bar, pot slot angle of inclination, and number of slots. The average velocity and interaction force curve of tea particles were obtained. The influence of the number of slots, the inclination angle of the slot, and the height of the convex bar on the effect of tea into strips were verified using a scheme design based on the quadratic regression orthogonal combination rotation test, and experimental research based on three factors and three levels was carried out. Design-Expert 11 software (Stat-Ease, Minneapolis, MN, USA) was used to optimize the response surface and analyze the regression model of the relevant test data. The 6CSL-800 tea de-enzyming (Anji Yuanfeng Tea Machinery Co., Ltd., Huzhou, China) and carding machine (Anji Yuanfeng Tea Machinery Co., Ltd., Huzhou, China) was used as the verification test prototype, six sets of verification tests were carried out, and the test results showed that the maximum value of the strip rate index and the minimum value of the broken tea rate index were obtained. The order of the indicators affecting the bar-type rate and broken tea rate of the de-enzyming and carding machine from high to low is as follows: the height of the convex bar, the inclination angle of the slot body, and the number of slots bodies. When the height of the convex bar was 10 mm, the inclination angle of the slot was 90°, the number of slots was 12, the bar-type rate was 89.45%, and the broken tea rate was 1.63%. The prediction results of the regression model of the bar-type rate and broken tea rate of the tea de-enzyming and carding machine were verified by employing six sets of control tests with the 6CSL-800 tea de-enzyming and carding machine as the validation test prototype. The actual values of the bar-type rate obtained from the six sets of control tests were 88.19%, 90.37%, and 87.33% (1,2,3 group), and the actual values of the broken tea rate were 1.66%, 1.69%, and 1.61% (4,5,6 group), with average values of 88.63% and 1.65%. The control test was basically consistent with the results of parameter optimization. The processed finished tea has good quality, which can provide theoretical reference for the optimization and design of tea de-enzyming and carding machines and similar tea machines in the future.

Parallel minimum mean square error equalization for reduced‐zero‐padding orthogonal time frequency space with the aid of unitary precoding

AbstractThis work studies the equalization method for the reduced‐prefix version of the orthogonal time frequency space (OTFS) modulation in which one zero‐padding (ZP) is inserted in each frame. We focus on applications in low data rate scenarios such as the Internet of Things, and will consider the case where the number of subcarriers and time slots are small. The idea of this work is to retain the large singular values of the channel matrix through linear transformations, while discarding the remaining small singular values. This makes it possible to avoid performance degradation due to small singular values when inverting the matrix in the minimum mean square error (MMSE) equalization. Specifically, a joint unitary precoding and signal linear transformation method is proposed for the reduced‐ZP OTFS modulation which decomposes the whole system into parallel subsystems. Then, the receiver can perform parallel MMSE equalization, where the singular values of each branch are not small. Simulation results show that the proposed method can achieve better bit error rate performance than the state‐of‐the‐art methods like message passing, unitary approximate message passing, and variational unitary approximate message passing.

Performance Improvement for double-stator permanent magnet synchronous machine using analytical subdomain model

An analytical subdomain model is employed in this paper for predicting the magnetic field distributions in a three-phase double-stator permanent magnet synchronous machine (DS-PMSM) during open-circuit and onload conditions. Due to the stator cores are located in the outer and inner parts of the motor, the DS-PMSM construction is quite complex. The rotor magnets are positioned between these two stators. The stator inner radius, stator outer radius, slot opening, magnet arc, magnet thickness, inner and outer air-gap thickness and number of windings turns will directly influence the motor performance in DS-PMSM. The analytical subdomain model employed in this paper has a significant advantage as a rapid design tool since it is capable of precisely predicting the performance of DS-PMSM while requiring less computational effort. The analytical model was initially created using the separation of variables technique in four subdomains based on the Poisson’s and Laplace’s equations: inner air-gap, inner magnet, outer magnet and outer air-gap. Applying the appropriate boundary and interface conditions yields the field solutions in each subdomain. Besides, the fractional DS-PMSM with different number of slots between outer and inner stators to rotor poles can result in low cogging torque and non-overlapping winding configuration. The analytical results are validated by Finite Element Analysis (FEA). The slotted air-gap flux density, back-emf, and output torque have all been evaluated as electromagnetic performances. The results demonstrate that the suggested analytical model is capable of accurately predicting the DS-PMSM performance.