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Empirical study on directional millimeter-wave propagation in vehicle-to-infrastructure communications between road and roadside

Xichen Liu, Lin Yang, Daizhong Yu,362475709@qq.com,eelyang@uestc.edu.cn,15908107465@163.com

Frontiers of Information Technology & Electronic Engineering 2021, Volume 22, Issue 4, Pages 503-516 doi: 10.1631/FITEE.2000464

Abstract: With the increased demand for unmanned driving technology and big-data transmission between vehicles, (mmWave) technology, due to its characteristics of large bandwidth and low latency, is considered to be the key technology in future vehicular communication systems. Different from traditional cellular communication, the vehicular communication environment has the characteristics of long distance and high moving speed. However, the existing communication channel tests mostly select low-speed and small-range communication scenarios for testing. The test results are insufficient to provide good data support for the existing vehicular communication research; therefore, in this paper, we carry out a large number of channel measurements in mmWave vehicle-to-infrastructure (V2I) long-distance communication scenarios in the 41 GHz band. We study the received signal strength (RSS) in detail and find that the vibration features of RSS can be best modeled by the modified considering road roughness. Based on the obtained RSS, a novel close-in (CI) model considering the effect of the transmitter (TX) and receiver (RX) antenna heights (CI-TRH model) is developed. As for the channel characteristics, the distribution of the root-mean-square (RMS) delay spread is analyzed. We also extend the two-section exponential (PDP) model to a more general form so that the distance-dependent features of the mmWave channel can be better modeled. Furthermore, the variation in both RMS delay spread and PDP shape parameters with TX-RX distance is analyzed. Analysis results show that TX and RX antenna heights have an effect on large-scale fading. Our modified , CI-TRH model, and two-section exponential PDP model are proved to be effective.

Keywords：毫米波；两径模型；均方根时延扩展；功率延迟分布；CI-TRH路径损耗模型

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A novel PV sub-module-level power-balancing topology for maximum power point tracking under partial shading and mismatch conditions Article

Mustafa GOKDAG,Mehmet AKBABA

Frontiers of Information Technology & Electronic Engineering 2016, Volume 17, Issue 12, Pages 1388-1396 doi: 10.1631/FITEE.1500322

Abstract: Partial shading and mismatch conditions among the series-connected modules/sub-modules suffer from a nonconvex power curve with multiple local maxima and decreased peak power for the whole string. Energy transfer between the sub-modules brings them to the same operating voltage, and this collective operation produces a convex power curve, which results in increased peak power for the string. The proposed topology benefits from the switched-capacitor (SC) converter concept and is an applica-tion for sub-module-level power balancing with some novelties, including stopping the switching in absence of shading, string-level extension, and a reduced number of power electronics components as compared to those in the literature. Reduction in the number of power electronics components is realized by the fact that two sub-modules share one SC converter. This leads to reduced power electronics losses as well as less cost and volume of the converter circuit. Insertion loss analysis of the topology is presented. The proposed topology is simulated in the PSpice environment, and a prototype is built for experimental verification. Both simulation and experimental results confirm the loss analysis. This proves that with the proposed topology it is possible to extract almost all the power available on the partially shaded string and transfer it to the load side.

Keywords： Sub-module-level maximum power point tracking (MPPT) Differential power processing (DPP) Distributed power converters Switched-capacitor (SC) converters

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Synergic Effect of Reworking for Imperfect Quality Items with the Integration of Multi-Period Delay-in-Payment and Partial Backordering in Global Supply Chains Article

Waqas Ahmed, Muhammad Moazzam, Biswajit Sarkar, Saif Ur Rehman

Engineering 2021, Volume 7, Issue 2, Pages 260-271 doi: 10.1016/j.eng.2020.07.022

Abstract:

In intercontinental trade and economics goods are bought from a global supplier. On occasion, the expected lot may include a fraction of defective items. These imperfect items still have worth and can be sold to customers after repair. It is cost-effective and sustainable to rework such items in nearby repair workshops rather than return them. The reworked items can be returned from the workshop to the buyer when shortages are equal to the quantity of imperfect items. In the meantime, the supplier correspondingly deals a multi-period delay-in-payments strategy with purchaser. The entire profit has been maximized with paybacks for interim financing. This study aims to develop a synergic inventory model to get the most profit by making an allowance for reworking, multi-period delay-in-payments policy, and shortages. The findings of the proposed model augment inventory management performance by monitoring cycle time as well as fraction of phase with optimistic inventory for a supply chain. The results demonstrate that profit is smaller if the permitted period given by supplier to buyer is equal to or greater than the cycle time, and profit is greater if the permitted period is smaller than the cycle time. The algebraic method is engaged to make a closed system optimum solution. The mathematical experiment of this study is constructed to provide management insights and tangible practices.

Keywords： Imperfect items Rework Shortages Multi-period delay-in-payments Non-derivative methodology

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ShortTail: taming tail latency for erasure-code-based in-memory systems Research Article

Yun TENG, Zhiyue LI, Jing HUANG, Guangyan ZHANG

Frontiers of Information Technology & Electronic Engineering 2022, Volume 23, Issue 11, Pages 1646-1657 doi: 10.1631/FITEE.2100566

Abstract:

s with erasure coding (EC) enabled are widely used to achieve high performance and data availability. However, as the scale of clusters grows, the server-level fail-slow problem is becoming increasingly frequent, which can create long . The influence of long is further amplified in EC-based systems due to the synchronous nature of multiple EC sub-operations. In this paper, we propose an EC-enabled in-memory storage system called ShortTail, which can achieve consistent performance and low latency for both reads and writes. First, ShortTail uses a lightweight request monitor to track the performance of each memory node and identify any fail-slow node. Second, ShortTail selectively performs degraded reads and redirected writes to avoid accessing fail-slow nodes. Finally, ShortTail posts an adaptive write strategy to reduce write amplification of s. We implement ShortTail on top of Memcached and compare it with two baseline systems. The experimental results show that ShortTail can reduce the P99 by up to 63.77%; it also brings significant improvements in the median latency and average latency.

Keywords： Erasure code In-memory system Node fail-slow Small write Tail latency

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A novel method for extending the output power back-off range of an asymmetrical Doherty power amplifier Research Article

Mingyu LI, Xiaobing CHENG, Zhijiang DAI, Kang ZHONG, Tianfu CAI, Chaoyi HUANG

Frontiers of Information Technology & Electronic Engineering 2023, Volume 24, Issue 3, Pages 470-479 doi: 10.1631/FITEE.2200250

Abstract: A novel method is proposed to extend the range of the . This study reveals that the OPBO range of the DPA can be extended by tuning the of the peaking stage away from infinity and changing the phase delay of the output matching network of the carrier power amplifier. Based on this theory, a large-OPBO-range high-efficiency asymmetrical DPA working band from 1.55 to 2.2 GHz (35% relative bandwidth) is designed to verify the proposed method. Experimental results show that the DPA operates from 1.6 to 2.1 GHz. The range of the measured efficiency is 42.2%–52.1% in the OPBO state and 47%–62.7% in the saturation state. The OPBO range is 11.1–13.2 dB.

Keywords： Doherty power amplifier (DPA) Output power back-off (OPBO) Output impedance Network phase

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Non-IID Recommender Systems: A Review and Framework of Recommendation Paradigm Shifting Artical

Longbing Cao

Engineering 2016, Volume 2, Issue 2, Pages 212-224 doi: 10.1016/J.ENG.2016.02.013

Abstract:

While recommendation plays an increasingly critical role in our living, study, work, and entertainment, the recommendations we receive are often for irrelevant, duplicate, or uninteresting products and services. A critical reason for such bad recommendations lies in the intrinsic assumption that recommended users and items are independent and identically distributed (IID) in existing theories and systems. Another phenomenon is that, while tremendous efforts have been made to model specific aspects of users or items, the overall user and item characteristics and their non-IIDness have been overlooked. In this paper, the non-IID nature and characteristics of recommendation are discussed, followed by the non-IID theoretical framework in order to build a deep and comprehensive understanding of the intrinsic nature of recommendation problems, from the perspective of both couplings and heterogeneity. This non-IID recommendation research triggers the paradigm shift from IID to non-IID recommendation research and can hopefully deliver informed, relevant, personalized, and actionable recommendations. It creates exciting new directions and fundamental solutions to address various complexities including cold-start, sparse data-based, cross-domain, group-based, and shilling attack-related issues.

Keywords： Independent and identically distributed (IID) Non-IID Heterogeneity Coupling relationship Coupling learning Relational learning IIDness learning Non-IIDness learning Recommender system Recommendation Non-IID recommendation

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Improved three-vector based dead-beat model predictive direct power control strategy for grid-connected inverters None

Chen-wen CHENG, Heng NIAN, Long-qi LI

Frontiers of Information Technology & Electronic Engineering 2018, Volume 19, Issue 11, Pages 1420-1431 doi: 10.1631/FITEE.1601874

Abstract:

Since only one inverter voltage vector is applied during each duty cycle, traditional model predictive direct power control (MPDPC) for grid-connected inverters (GCIs) results in serious harmonics in current and power. Moreover, a high sampling frequency is needed to ensure satisfactory steady-state performance, which is contradictory to its long execution time due to the iterative prediction calculations. To solve these problems, a novel dead-beat MPDPC strategy is proposed, using two active inverter voltage vectors and one zero inverter voltage vector during each duty cycle. Adoption of three inverter vectors ensures a constant switching frequency. Thus, smooth steady-state performance of both current and power can be obtained. Unlike the traditional three-vector based MPDPC strategy, the proposed three vectors are selected based on the power errors rather than the sector where the grid voltage vector is located, which ensures that the duration times of the selected vectors are positive all the time. Iterative calculations of the cost function in traditional predictive control are also removed, which makes the proposed strategy easy to implement on digital signal processors (DSPs) for industrial applications. Results of experiments based on a 1 kW inverter setup validate the feasibility of the proposed three-vector based dead-beat MPDPC strategy.

Keywords： Grid-connected inverter Model predictive control Direct power control Three vectors Constant switching frequency Power errors

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United Algorithm for Dynamic Subcarrier, Bit and Power Allocation in OFDM System

Gao Huanqin,Feng Guangzeng,Zhuqi

Strategic Study of CAE 2006, Volume 8, Issue 3, Pages 62-65

Abstract:

A realtime united algorithm for dynamic subbcarrier, bit and power allocation according to the change of channel (UA) is presented in this paper, which can be used into the down-link of multi-user orthogonal frequency division multiplexing (OFDM) system. With the algorithm the total transmission power is the minimum while the data rate of each user and the required BER performance can be achieved. Comparing to the subcarrier allocation algorithm (WSA) , the simulation results show that the algorithm presented in this paper has better performance while both have equal calculating complexity.

Keywords： OFDM Wong's subcarrier allocation (WSA) UA

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Research on the variable speed technology of large power alternating current motor

Li Chongjian

Strategic Study of CAE 2009, Volume 11, Issue 5, Pages 31-36

Abstract:

In this paper, the development status of the domestic large power AC motor variable frequency speed regulation technology is introduced. The domestic large power AC drivers fed by cycloconverters have been greatly developed, and some innovation on the theory and engineering technique has been realized. They have been applied to rolling mill, mine winder and so on, and remarkable economic and social benefit has been achieved. The development of the first domestic 7.5 MVA IGCT AC-DC (direct current)-AC converter is also introduced. This converter has excellent performance and reliable operation, and it has been used in traction.

Keywords： large power AC motor cycloconverter AC-DC-AC converter IGCT

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PSD Analysis on Track Irregularity of Railway Linefor Passenger Transport

Chen Xiufang,Jin Shouhua,Zeng Hualiang

Strategic Study of CAE 2008, Volume 10, Issue 4, Pages 56-59

Abstract:

The track irregularity which is the main vibrating resource of the vehicles and one of the main factors to limit the train highest speed, plays a very important part in the safety, stabilization and comfort of the trains. The statistic samples used by this paper are collected by track geometry inspection car from Qin-shen special line for passenger transport. Based on the stationary character test of the samples, FFT method was used to evaluate the spectrum of the statistical sample space, and MATLAB soft was used to get the PSD(power spectral sensity) of track irregularities. Based on statistical average of the samples of the track irregularities, frequency smoothing of the PSD and coupare with PSD of the main-line of Chinese railway were made. The curve to the PSD was fit. Then the track state of Qin+shen special line for passenger transport was evaluated.

Keywords： railway line for passenger transport track irregularity power spectral density stationary character test

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Reasonable Rated Voltage of High and Medium Power Adjustable-Speed Drives for Energy Saving

Ma Xiaoliang

Strategic Study of CAE 2001, Volume 3, Issue 11, Pages 80-84

Abstract:

A large amount of energy will be saved if adjustable-speed drives are adopted by high and medium power pumps and fans. The power range of most of the drives is within 0.2～2 MW. The rated voltage of most of the motors in the power range is 10 kV because the power supply is 10 kV. The adjustable-speed scheme, a 10 kV motor is fed by a 10 kV inverter, is not reasonable because this kind of inverter consists of a lot of power electronic devices in series and its cost is high and reliability is poorer than lower voltage one. Owing to the existence of input transformer of the inverter, it is not necessary to ask for that the rated voltage of the motor and inverter is the same as power supply, i. e. a lower rated voltage can be used for the motor and inverter. The reasonable rated voltages of motors and inverters with different power grades are investigated and the by-pass methods when the rated voltages of the motors are different from power supply are discussed in this paper.

Keywords： high and medium power adjustable-speed drives for energy saving reasonable rated voltage low voltage inverters medium voltage inverters by-pass

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Technological Approaches to Increasing Specific Power of Vehicular Fuel Cell Stacks

Hou Ming, Shao Zhigang, Yi Baolian

Strategic Study of CAE 2019, Volume 21, Issue 3, Pages 84-91 doi: 10.15302/J-SSCAE-2019.03.002

Abstract:

As a type of new energy vehicle, fuel cell vehicle has attracted increasing attention because of its long driving distance, high power performance, fast fuel filling, and compatibility with renewable energies. Fuel cell stack is the core of a fuel cell vehicle, and specific power indicates the technical level of a fuel cell stack. Using a high-specific-power fuel cell stack technology, the number of stack hardware can be reduced, so the cost of stacks can be significantly lowered. The most advanced fuel cell stack can provide high power in a limited vehicular space owing to its high specific power. However, the specific power of stacks in China still lags behind the advanced level in the world. In this paper, the technical approaches to improving the specific power of the fuel cell stack are discussed, from the aspects of highly active catalyst, enhanced composite proton exchange membrane, high disturbance flow field, conductive and corrosion-resistant thin-metal bipolar plates, as well as assembly and consistency of stacks. Based on the accumulation of theories and from practices, the relevance between the activation/ohmic/mass transfer polarization of fuel cells and materials/components/assembly is analyzed, which provides a reference for further improving the performance and specific power of fuel cell stacks.

Keywords： fuel cell vehicle fuel cell stack performance specific power

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Research on Raising Heat-power of the Gear Reducer With Middle-power

Hu Rufu,Zhang Dongsu

Strategic Study of CAE 2004, Volume 6, Issue 4, Pages 72-76

Abstract:

Heat-power is an impartment performance index to choose the gear reducer. The working efficiency of the gear reducer lies on the value of the heat-power when working with the temperature at which heat balance is achieved. Raising Heat-power will benefit working efficiency, and reduce the waste of energy sources. The formula to calculate efficiency is deduced, and the heat-power is tested by way of experiment. The heat-radiating equipments with the structures of plank-lumped and pipe-ranked are developed. On the basis of this, the methods are brought forward to raise heat-power of gear reducers considering the factors of designing, manufacturing and lubricating.

Keywords： gear-reducer heat-power heat-efficiency heat-radiating equipment

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Dynamic power-gating for leakage power reduction in FPGAs Research Article

Hadi JAHANIRAD,h.jahanirad@uok.ac.ir

Frontiers of Information Technology & Electronic Engineering 2023, Volume 24, Issue 4, Pages 582-598 doi: 10.1631/FITEE.2200084

Abstract: devices have become widespread in electronic systems due to their low design costs and reconfigurability. In battery-restricted applications such as handheld electronics systems, low-power FPGAs are in great demand. almost equals dynamic power in modern integrated circuit technologies, so the reduction of leads to significant energy savings. We propose a power-efficient architecture for static random access memory (SRAM) based FPGAs, in which two modes (active mode and sleep mode) are defined for each module. In sleep mode, ultra-low is consumed by the module. The module mode changes dynamically from sleep mode to active mode when module outputs evaluate for new input vectors. After producing the correct outputs, the module returns to sleep mode. The proposed circuit design reduces the consumption in both active and sleep modes. The proposed low-leakage FPGA architecture is compared with state-of-the-art architectures by implementing Microelectronics Center of North Carolina (MCNC) benchmark circuits on FPGA-SPICE software. Simulation results show an approximately 95% reduction in consumption in sleep mode. Moreover, the total power consumption (leakage+dynamic power consumption) is reduced by more than 15% compared with that of the best previous design. The average area overhead (4.26%) is less than those of other designs.

Keywords： Field programmable gate array (FPGA) Leakage power Power-gating Transistor-level circuit design

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Status of High-power Solid-state Lasers and Engineering Science

Peng Hansheng,Zhang Xiaomin,Fan Dianyuan,Zhu Jianqiang

Strategic Study of CAE 2001, Volume 3, Issue 3, Pages 1-8

Abstract:

High-power solid-state laser technology development has been conducted so far for more than thirty years for application to inertial confinement fusion. Over twenty laser facilities have been built with the output energy of about a hundred Joules at the beginning up to severa tens of thousands Joules later in USA, Japan, France, China, Bratain, Russia and so on. In recent years, a few powers have been working very hard to build huge facilities, such as the NIF in USA, the LMJ in France, the SG—Ⅲ in China and the Iskra-6 in Russia. Numerous advanced technologies have to be developed to support the construction of the facilities. However, the most challenging task is to study, from the point of view of engineering science, how to build such huge facilities featured with high cost, high technical risk, and a long time period, in a cost-effective manner.

Keywords： laser fusion high-power solid-state laser status engineering science innovation

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Title Author Date Type Operation

Empirical study on directional millimeter-wave propagation in vehicle-to-infrastructure communications between road and roadside

Xichen Liu, Lin Yang, Daizhong Yu,362475709@qq.com,eelyang@uestc.edu.cn,15908107465@163.com

Journal Article

A novel PV sub-module-level power-balancing topology for maximum power point tracking under partial shading and mismatch conditions

Mustafa GOKDAG,Mehmet AKBABA

Journal Article

Synergic Effect of Reworking for Imperfect Quality Items with the Integration of Multi-Period Delay-in-Payment and Partial Backordering in Global Supply Chains

Waqas Ahmed, Muhammad Moazzam, Biswajit Sarkar, Saif Ur Rehman

Journal Article

ShortTail: taming tail latency for erasure-code-based in-memory systems

Yun TENG, Zhiyue LI, Jing HUANG, Guangyan ZHANG

Journal Article

A novel method for extending the output power back-off range of an asymmetrical Doherty power amplifier

Mingyu LI, Xiaobing CHENG, Zhijiang DAI, Kang ZHONG, Tianfu CAI, Chaoyi HUANG

Journal Article

Non-IID Recommender Systems: A Review and Framework of Recommendation Paradigm Shifting

Longbing Cao

Journal Article

Improved three-vector based dead-beat model predictive direct power control strategy for grid-connected inverters