Users’ Perception on Operation and Performance of Public Transport Systems in African Developing Countries: The Case of Bus Rapid Transit (BRT) in Dar es Salaam City, Tanzania

Public transport system has been a means of addressing transportation challenges in urban areas, such as traffic congestion, traffic jam and long travel time in cities worldwide. Transportation in Africa is unique in that it has the least developed public transport systems in the world, while also being one of the fastest urbanizing continents. Bus Rapid Transit being one of the public transport systems was introduced in Africa in 2008 as a means to provide solution on urban transportation challenges. Despite of public transport being the main means of transport in African developing countries, there have been a number of challenges that affects efficiency of performance of the system and makes its users uncomfortable. Therefore, the study aimed at exploring the setbacks or challenges associated with operation and performance of the BRT system in the African developing countries and address them. The study employed mixed methods research design that integrates both qualitative and quantitative data collection methods and analysis. The study findings reveal that, there is an improvement on the perspectives of the commuters on public transport after introduction of BRT system. However, some challenges such as long waiting time, passengers overcrowding during peak hours, as well as safety and security can slowly change the perspective of the commuters. Therefore, to address these challenges it is recommended to reduce the long waiting time and improve accessibility by introduction of passenger information displays (bus information system) and automated fare collection system;reduce travel time by introduction of bus priority signal;and improve safety and security by introduction of signage and CCTV Camera within the bus and bus stops.

1D/3D Coupling Calculation Analysis on Bus Cooling System

Compared with front engine vehicle, the windward side’s flow field in cooling model of rear engine bus is complicated and it can’t be calculated by means of 1D model. For this problem, this paper has used Star-CCM to build a 3D simulation model of cooling system, engine compartment and complete vehicle. Then, it had a 1D/3D coupling calculation on cooling system with Kuli software. It could be helpful in the optimization design of the flow field of rear engine compartment and optimization match of cooling system.

Study and Analysis of Bus Arbitration Mechanism in PI-MPS Multiprocessor System

This paper presents the mechanism of the bus arbitration in PI-MPS multiprocessor sys-tem,describes encode approach,arbiter timing states and uniqueness of master modular ininterconnection bus,and measures and analyses latency of bus arbitration as well.

Using a Health Level 7 Interoperability Bus to Support Legacy Systems in the Health Domain

In order to reduce the effort in the integration and actualization of heterogeneous healthcare legacy systems that should share a common database, we propose the creation of an interoperability bus using the HL7 standard—the HL7Middleware. This interoperability bus is an intermediate layer responsible for the communication between a database, health information systems and medical equipment, called HL7Server. Connected systems use the HL7 messaging semantics to store and retrieve data from the database. We validate our approach with respect to two different criteria: performance and integration costs. Benchmark tests were executed with and without the use of HL7Middleware and with different network bandwidths. These results demonstrated that the performance of the interoperability bus is higher when compared to traditional database access for larger volumes of data and when the bandwidth of the user is considerably lower than the bandwidth of the connection between HL7Server and database. The overall development and deployment cost was considered low and the reusability degree of wrapper code was considered high, thus suggesting a progressive reduction of the integration costs of additional services and subsystems of an organization.

Investigating the Effects of Slack Bus Selection in Load Flow Studies: A Comparative Analysis of Robust and Weak Grids

Load flow studies play a critical role in the analysis of power systems. They enable the computation of voltage, current, and power flows in a power system. They provide valuable insights into the steady-state performance of the power system under different operating conditions. Choosing a slack bus is a vital step in conducting load flow simulations. A slack bus is a PV bus that includes a generator and is used to balance real and reactive power during load flow studies. Many studies have been conducted on the selection of slack buses in load flow analysis. However, varied conclusions regarding the impact on system losses and power flows were obtained during these studies. Therefore, using the IEEE-14 bus test system, this study investigated the effects of slack bus selection in strong and weak grids by alternating slack buses among PV buses and observing the effects on bus voltage magnitude, bus voltage phase angle, total power flows, and active and reactive power losses. The study noted that the effect of slack bus selection on these system quantities is contingent upon the voltage stability of the grid. Whereas in a robust grid, system losses and power flows remained constant irrespective of the choice of slack bus, a weak grid experienced some variations in these system quantities under similar circumstances. The simulation results led to the conclusion that, to a large extent, the voltage stability of the grid plays a significant role in determining the degree to which slack bus selection affects system losses and other quantities in load flow studies.

Shaping a New Level of Bus Service under a Novel Concept of Bus Interaction: A Meta-Review

Public transport services, particularly bus services, play an important role in a sustainable transportation system. However, despite various efforts, bus ridership has decreased. The appearance of shared and on-demand vehicle services is one of the main reasons for this issue. In addition, bus tourism services have been successfully developed to meet the exigent needs of tourists. Therefore, a new level of daily bus service is necessary to adapt to the changing demands of customers. Bus interaction (BI) plays an important role in bus services. Nevertheless, the conventional concept of BI mainly refers to users, physical interaction, and safety, but it does not address non-users, non-physical interactions, service quality, and other aspects. This study aims to elaborate on a new concept of bus services. Based on this, we developed a theoretical framework for BI. A meta-analysis was then conducted to identify the achievements and untouched aspects. The results of this study provide three main contributions. First, an unprecedented novel concept of BI is defined, including 13 types of interactions. Second, a comprehensive theoretical framework of BI is established based on the relationships between eight sustainable bus system sub-aspects and 13 BI types. Third, based on the theoretical framework and findings of the reviewed studies, a common finding comprehensive framework of BI is completed, which is accompanied by 1) key findings of the 13 BI types, 2) conclusions of traffic conditions affecting BI research, 3) BI research gaps, and 4) 16 main suggestions for future BI research.

团队年轻化生产设计更加优化和现代化 访Burmester CEO Frank Weise

在8月的“香港高级视听展”会上,我们有幸见到Burmester CEO Frank Weise,并与他进行了愉快的交流。作为在疫情期间才上任的Weise先生,自信心很强,并就明星产品和新产品作了简单的介绍。

Analysis of Control Characteristic for the Drive System of Electric Transit Bus

The drive control system of the permanent magnetic direct current motor with the enhanced magnetism windings used in the electric transit bus is developed. The mathematics model of the drive control system for this motor is established. The new mode that the added exiting magnetism field could be weakened and the speed of the motor could be controlled automatically is proposed and realized. The method of root locus design is applied to analyze the acceleration control characteristic. The results of simulation show that the new drive motor control system has extraordinary response characteristic and adjustable performance. Experiments of vehicle running show that the drive control system's antijamming ability is strong and the adjustable performance is fast and smooth, it can meet the demand of power characteristic very well.

基于1553B总线的大规模信息系统设计问题研究

某大型航天器GNC系统应用1553B总线构建了其规模庞大的信息系统,在信息系统设计过程中产生了3个问题:超长总线下的稳定通信、应用层协议的设计、多条总线的管理等。对这3个问题开展研究,描述了3个问题的由来,给出了问题的解决方法,并验证了方法的实际效果。结果表明:总线中继的方法,有效解决了1553B总线在240 m长度下的稳定可靠通信问题;广播帧计数回传的应用层协议,节省了总线数据通讯开销、并提供了丰富的故障诊断信息;遍历寻优的总线管理策略,最大程度上发挥了多机多总线系统的容错能力。

Application of CAN Bus in Hotel Guest Room Service and Management System

Technical features about CAN bus are described. One kind of scheme in Hotel Guest Room Service and Management System based on CAN bus is presented. The system's structure and main function are expounded. The work principle and design of the system's hardware and software are explained. The realization of the system's hardware and software is detailed from aspects of improving system's anti-jamming and fault self-examined capability, and the block diagram of each part's circuit is given. Finally, features of the system are summarized, and a comparison with the system based on RS485 was made to prove the advantages of the system. By practice, CAN bus in the system can transmit data steadily and reliably.

新型混合式贯通牵引供电系统及其复合控制策略

电分相与负序等电能质量问题是制约电气化铁路向高速化、重载化发展的桎梏。贯通牵引供电系统为消弭上述问题提供了契机,但既有贯通方案依然存在所需器件数目多、改造成本高、可靠性差等弊端。为此,在充分利用既有牵引变压器基础上,该文设计一种新型混合式贯通牵引供电装置。该装置通过共直流侧与功率均分手段有效抵消输入侧纹波功率,降低有源/无源器件数目与电容容量。同时,针对直流侧二次纹波与负荷功率冲击,提出一种输入端口复合控制策略,有效解决纹波传递与冲击波动问题。最后通过仿真与实验验证所提装置及其控制策略的可行性与可靠性。

Load Dependent Series-Parallel Systems with Common Bus Performance Sharing Mechanism

A series-parallel system was proposed with common bus performance sharing in which the performance and failure rate of the element depended on the load it was carrying. In such a system,the surplus performance of a sub-system can be transmitted to other deficient sub-systems. The transmission capacity of the common bus performance sharing mechanism is a random variable. Effects of load on element performance and failure rate were considered in this paper. A reliability evaluation algorithm based on the universal generating function technique was suggested. Numerical experiments were conducted to illustrate the algorithm.

含时滞的不确定性交直流微电网直流母线电压H_∞控制

针对含通信网络延时的不确定性交直流微电网的直流母线电压稳定问题,提出了一种将状态空间法和阻抗分析法相融合的方法,构建具有时滞的范数有界不确定交直流微电网模型。基于系统鲁棒二次稳定的求解,获得了满足H_∞控制性能的时滞无关型状态反馈控制器的条件。然后应用S-procedure定理,提出一种降低时滞依赖型Lyapunov方法的泛函构造难度且无须再次求导的方法,引用Wirtinger积分不等式和自由矩阵的积分不等式,得到时滞依赖型的H_∞控制器。仿真分析验证了所提控制方法能在一定的通信延时约束下抑制不确定参数对直流母线电压的影响。

基于Modbus双路RS485总线在实验室变风量控制系统中的应用

实验室变风量控制系统通过快速响应和精准控制在提升实验室安全性和“双碳”背景下的节能减排中发挥着重要作用。针对实验室变风量控制中实时快速控制和数据通信并存的需求,文章提出一种控制总线和数据总线双路RS485总线解决方案。通过双路RS485总线连接主机与从机,在不影响数据上传与交互条件下,有效提高了即时控制指令的下发与执行效率。

Windows and Fieldbus Based Software Computer Numerical Control System

Computer numerical control(CNC)system is the base of modern digital and intelligent manufacturing technolo- gy.And opened its architecture and constituted based on PC and Windows operating system(OS)is the main trend of CNC sys- tem.However,even if the highest system priority is used in user mode,real-time capability of Windows(2000,NT,XP)for applications is not guaranteed.By using a device driver,which is running in kernel mode,the real time performance of Windows can be enhanced greatly.The acknowledgment performance of Windows to peripheral interrupts was evaluated.Harmonized with an intelligent real-time serial communication bus(RTSB),strict real-time performance can be achieved in Windows platform. An opened architecture software CNC system which is hardware independence is proposed based on PC and RTSB.A numerical control real time kernel(NCRTK),which is implemented as a device driver on Windows,is used to perform the NC tasks.Tasks are divided into real-time and non real-time.Real-time task is running in kernel mode and non real-time task is running in user mode.Data are exchanged between kernel and user mode by DMA and Windows Messages.

n-Bu_2SnO催化酯交换合成碳酸二苯酯的研究

研究比较了 n-Bu2 Sn O、Ti( OC4H9) 4、Al Cl3、Zn Cl2 四种化合物催化酯交换合成碳酸二苯酯 ( DPC)的催化性能 ,其中n-Bu2 Sn O的催化活性最高。在常压下 ,160～ 190℃时 ,n(苯酚 )∶n(碳酸二苯酯 )∶ n( n-Bu2 Sn O) =4∶ 1∶ 0 .0 4,反应时间 14 h,碳酸二甲酯 ( DMC)的转化率为 48.5 % ,DPC的产率为 43 .0 % ,碳酸甲苯酯 ( MPC)产率 5 .5 %。 DPC的选择性 88.7% 。

基于C8051F040单片机+BU61580架构的1555B总线通信接口模块的设计

为掌握不同通信传输方式下1553B总线通信过程与协议芯片BU61580工作原理,针对目前国内外1553B总线通信接口模块的研制现状,研制出一种基于C8051F040单片机+BU61580架构的1555B总线通信接口模块,对该模块的硬件与软件分别进行设计,给出该模块在设计过程中应注意的问题,并以研华工控机内嵌GE多功能PCI-1553B总线板卡为上位机,以该模块为下位机,针对BC→RT、BC←RT、RT←→RT、广播消息以及方式指令5种通信传输方式,对该模块的功能进行试验验证,结果表明了其有效性。

含BuNENA钝感交联改性双基推进剂能量分析

利用推进剂配方理论计算程序,计算了Bu NENA钝感交联改性双基推进剂的能量性能。结果表明,标准理论比冲随粘合剂GAP/NC比例和增塑比的变化很小;随固体含量、固体填料RDX/AP/Al配比的变化很大。CL-20取代AP后,Bu NENA推进剂在固体含量为70%,其中CL-20为39%~52%范围内（相应的Al粉含量在7%~10%范围）,都可得到2700N·s/kg以上的理论比冲值,是一个有潜力的集高能、钝感、低特征信号于一身的推进剂体系。

基于BU—61580与USB的MIL—STD—1553B总线控制卡的设计

MIL—STD—1553B总线是一种军用串行总线,具有完整的总线通信协议,具有很高的可靠性,在航空、航天、汽车电子等领域有广泛的应用。USB总线是一种常用的通用串行总线。USB完整的通信协议使得USB传输具有很高的传输速率,接口通用性强等优点。为了在地面测得飞机或者卫星等应用上的1553B总线通信是否正常,需要专门的总线控制卡来进行通信测试。介绍了一种基于BU—61580和USB芯片设计的1553总线控制卡,该控制卡实现1553B总线控制的基本功能,包括读取和发送数据,发送方式控制字,向总线广播数据等基本的总线消息。同时继承了USB的各种优点,即支持即插即用功能,传输速度高,支持可编程的消息控制模式。并且介绍了这种总线控制卡的实现方法,包括BU—61580与USB芯片的硬件连接和软件实现,最后介绍了控制卡的测试结果。