Renewable energy supply chains,performance, application barriers,and strategies for further development

Due to the depletion of traditional energy resources, such as crude oil, coal, and natural gas, many initiatives all over the world have addressed the efficient use or replacement of these resources. Several renewable energy sources have been introduced as alternatives to traditional sources to protect environmental resources and to improve the quality of life. This study assesses renewable energy sources from a supply chain perspective and presents an investigation of renewable energies focusing on four main components: renewable energy supply chain, renewable energy performance, and barriers and strategies to its development. The study provides managerial insights to governments, researchers, and stakeholders for the initiation of renewable energy use, and suggestions for overcoming the barriers to its development.     

Microstructural fabrication and design of sunlight guide panels of inorganic-organic hybrid material

This study demonstrates a sunlight guide panel with a UV-imprinted microstructure that improves sunlight utilization in buildings. The panel that was assembled to the transoms of a building guides sunlight from outdoors to enhance indoor lighting. To match the requirements of outdoor applications, an inorganic-organic hybrid material was adopted for high weather resistance and transparency. An optical analysis was conducted for outgoing angles of sunlight through the guide panel to study the effect of the angle of solar elevation, wavelength of the sunlight, wear ratio of the microstructure, and scale of the microstructure. The micropatterns of the panel included 90° feature with pitches of 50 and 100 μm, as well as 45° feature with pitch of 50 μm. The experimental results showed good pattern fidelity and a high energy efficiency in the imprinted panel. The optical performance of the sunlight guide panel was measured and found to be consistent with the simulated prediction.     

Effect of rapid thermal annealing on pentacene-based thin-film transistors

The bottom contact pentacene-based thin-film transistor is fabricated, and it is treated by rapid thermal annealing (RTA) with the annealed temperature up to 240 °C for 2 min in the vacuum of 1.3 × 10⁻² torr. The morphology and structure for the pentacene films of OTFTs were examined by scanning electron microscopy and X-ray diffraction technique. The thin-film phase and a very small fraction of single-crystal phase were found in the as-deposited pentacene films. While the annealing temperature increases to 60 °C, the pentacene molecular ordering was significantly improved though the grain size only slightly increased. The device annealed at temperature of 120 °C has optimal electrical properties, being consistent with the experimental results of XRD. The post-annealing treatment results in the enhancement of field-effect mobility in pentacene-based thin-film transistors. The field-effect mobility increases from 0.243 cm²/V s to 0.62 cm²/V s. Besides, the threshold voltage of device shifts from −7 V to −3.88 V and the on/off current ratio increases from 4.0 × 10³ to 8.7 × 10³.     

Synchronous multicast and broadcast service in multi-rate IEEE 802.16j WiMAX relay network

IEEE 802.16j Mobile Multihop Relay Standard defines multi-hop relay operation in a WiMAX system. It uses a novel synchronous multicast and broadcast transmission mechanism to achieve macro diversity. With the newly introduced synchronous delivery constraint, the multicast data delivery algorithm should be designed differently to enhance system performance. This paper provides Multi-Rate Selection Algorithm (MRSA) for multicast and broadcast (MBS) data delivery. It could reduce the data distribution delay from the BS to all the RSs. Besides, we also propose the path selection algorithm to further improve the effectiveness of MRSA. Our simulation results show that using MRSA with our shortest-path path selection algorithm, the delay for data delivery in 802.16j MBS system could be greatly reduced. The proposed scheme could achieve the performance closed to the optimal solutions. To the authors’ best knowledge, this is the first research work to investigate the IEEE 802.16j multicast and broadcast problem.     

Modeling and analysis of applying adaptive modulation coding in wireless multicast and broadcast systems

Traditional wireless communications only utilize fixed-rate multicast and broadcast. In other words, only the most robust modulation and coding scheme can be applied for data transmission. Such a scheme fails to sufficiently exploit the potential gains of multicast and broadcast, resulting in bandwidth waste. To overcome such a problem, investigating the rate adaptation of multicast and broadcast wireless systems is the primary task. Unlike the traditional wireless systems, this paper presents an analytical model with rate adaptation for both multicast and broadcast. Adaptive modulation and coding are applied to achieve rate adaptation. We construct a stochastic model by using Finite State Markov chains for the multicast broadcast system modeling. The model’s outputs are shown to approximate to the results of our system level simulations. The model derives the performance of rate adaptation in multicast and broadcast. With the deduced modeling results, we can predict the system throughput providing the channel states, and the modulation and coding schemes variations.     

A simulated annealing for hybrid flow shop scheduling with multiprocessor tasks to minimize makespan

This paper studies a hybrid flow shop scheduling problem (hybrid FSSP) with multiprocessor tasks, in which a set of independent jobs with distinct processor requirements and processing times must be processed in a k-stage flow shop to minimize the makespan criterion. This problem is known to be strongly nondeterministic polynomial time (NP)-hard, thus providing a challenging area for meta-heuristic approaches. This paper develops a simulated annealing (SA) algorithm in which three decode methods (list scheduling, permutation scheduling, and first-fit method) are used to obtain the objective function value for the problem. Additionally, a new neighborhood mechanism is combined with the proposed SA for generating neighbor solutions. The proposed SA is tested on two benchmark problems from the literature. The results show that the proposed SA is an efficient approach in solving hybrid FSSP with multiprocessor tasks, especially for large problems.     

大连国际会议中心关键施工技术

大连国际会议中心造型奇特,结构复杂。首先介绍了工程特点、难点,阐述了具体施工技术,从钢结构节点深化设计、宽翼缘箱形空间弯扭钢柱制作及安装、复杂劲性核心筒施工、管桁架屋盖安装、钢结构合拢、临时支撑架卸载及焊接质量控制等方面对结构施工关键技术进行介绍。实践表明,工程满足施工质量要求。     

A latency-aware scheduling algorithm for all-optical packet switching networks with FDL buffers

Optical buffers implemented by fiber delay lines (FDLs) have a volatile nature due to signal loss and noise accumulation. Packets suffer from excessive recirculation through FDLs, and they may be dropped eventually in their routing paths. Because of this, packet scheduling becomes more difficult in FDL buffers than in RAM buffers, and requires additional design considerations for reducing packet loss. We propose a latency-aware scheduling scheme and an analytical model for all-optical packet switching networks with FDL buffers. The latency-aware scheduling scheme is intended to minimize the packet loss rate of the networks by ranking packets in the optimal balance between latency and residual distance. The analytical model is based on non-homogeneous Markovian analysis to study the effect of the proposed scheduling scheme on packet loss rate and average delay. Furthermore, our numerical results show how various network parameters affect the optimal balance. We demonstrate quantitatively how to achieve the proper balance between latency and residual distance so that the network performance can be improved significantly. For instance, we find that under a given latency limit and light traffic load our scheduling scheme achieves a packet loss rate 71% lower than a scheduling scheme that ranks packets simply based on latency.     

AZ31与AZ61异种镁合金的TIG焊研究

采用TIG焊对AZ31与AZ61镁合金薄板进行连接,分别采用了AZ31和AZ61焊丝,比较焊接效果的影响.通过显微镜、扫描电镜、X-ray物相检测等实验方法,分析了两种焊丝焊接接头的外观形貌、显微组织、焊缝析出相及力学性能等差异.研究结果表明:采用AZ31和AZ61两种焊丝都能完成AZ31与AZ61镁合金薄板的对焊,获...     

Preparation of High-Quality FeV55N Using Ammonia as a Reductant and Nitrogen Source

High-quality FeV55N has been prepared by using ammonia as a reductant and nitrogen source. The raw materials comprised ammonium vanadate and Fe₂O₃, which were first reduced and nitrided by ammonia to prepare FeV55N composite powders of VN and Fe₂N. Subsequently, the composite powders were sintered at high temperature to obtain a bulk FeV55N alloy. The final products obtained by this method do not contain elemental Al, Si, or C impurities. Furthermore, the residual oxygen content of the final products can be reduced to 0.56 wt.%. After sintering, it is possible to obtain a FeV55N alloy with a density of up to 5.4 g/cm³.