Experimental verification of shock sterilization for marine <Emphasis Type="Italic">Vibrio</Emphasis> sp. using microbubbles interacting with underwater shock waves

In this paper, shock sterilization using the motions of microbubbles induced by underwater shock waves is verified experimentally. A bio-experiment is carried out using marine Vibrio sp.. Underwater shock waves are produced by electric discharge in a semi-ellipsoidal discharge reflector. The shock waves are focused to increase the pressure that the generated microbubbles are exposed to. The microbubbles are generated independently. The microbubble generator can produce microbubbles of around 50 μm diameter by means of Kelvin–Helmholz instability and Venturi effect. Propagation behavior of shock waves and generation process of microbubbles are captured by high-speed camera. The experimental results show that the supply of microbubbles increases the potential of shock sterilization. In addition, it is found that shock waves without microbubbles also have the capacity of sterilization, and this means that cavitation bubbles generated behind converging shock waves contribute to inactivating marine bacteria.     

Nonlinear model predictive dynamic positioning control of an underwater vehicle with an onboard USBL system

This paper presents a novel optimization-based approach for dynamic positioning (DP) of a fully actuated underwater vehicle equipped with an onboard ultrashort baseline transceiver to provide relative position information of two earth-fixed transponders near the vehicle. The DP system error is defined by the transponders’ positions compared to the desired values, which occur at the vehicle’s target pose (position and orientation). The proposed DP strategy is composed of two loops in a hierarchical structure. In the kinematic loop, the nonlinear model predictive control is used to generate the desired velocity by optimizing a cost function of the predictive trajectories under the constraints of velocity and transponder bearings over a limited time horizon. In the dynamic loop, the neural network model reference adaptive control with pseudo control hedging is utilized to ensure the asymptotical convergence of velocity tracking errors in the presence of uncertainties associated with unknown model parameters, currents and thruster dynamics. The effectiveness of the proposed control scheme is illustrated by comprehensive simulations.     

功能状态下无牙颌患者髁状突的应力分布研究

目的构建无牙颌包括下颌骨的颞下颌关节(TMJ)三维有限元模型;探讨戴用全口义齿无牙颌患者在牙尖交错位紧咬牙时颞下颌关节髁状突的应力分布特征。方法以活体人颅为标本,采用螺旋CT断层扫描技术,图像数字化处理等方法在计算机上构建模型,然后在载荷状态下,利用ANSYSV8.0软件进行运算分析。结果建立了无牙颌下颌骨和颞下颌关节三维有限元模型,并在此模型后牙相应位点加载、运算、分析显示:髁突近颈部应力力值明显大于近顶区;前、后斜面由外向内力值逐渐减小;外、内侧由前向后力值逐渐减小,前斜面、外侧上1/2(近髁突顶)区域压应力占主导地位,下1/2(近颈区)区域以拉应力为主,下外侧为主要应力集中区;后斜面及内侧上1/2以拉应力为主,下1/2以压应力为主。结论戴用息止间隙为2mm的全口义齿无牙颌患者,髁状突各区域拉、压应力并存,但每个区域应力分布特征及水平有较大差异;前斜面外侧即关节功能区应力水平明显高于其他区域,符合正常人TMJ功能的特点。     

dSPACE 快速控制原型在十五相感应电动机驱动系统中的应用研究

为了提高功率密度,需要在十五相感应电动机驱动系统输出电压中注入三次谐波,这势必导致控制系统的复杂化.本文使用基于dSPACE的快速控制原型方法,在MATLAB/SIMULINK环境中建立控制系统的仿真模型,以控制真实的十五相逆变器,快速构建该电机驱动系统,并利用ControlDesk软件开发后期管理和监控平台.研究表明,所建立的半实物仿真驱动系统,具有较高的有效性和可行性,且便于快速修改控制结构和相关参数.     

基于市场细分的郊区轨道交通客流分析

介绍了市场细分的前提、市场细分的标准和方法等基本概念.以上海为例,对轨道交通客流需求市场细分流程提出了建议.选取"郊区轨道交通客流"作为未来上海轨道交通运营企业的目标子市场,设计一系列营销策略,吸引和培育郊区轨道交通客流,以促进城市轨道交通的良性发展.     

Model,process, technique,and the good thing

The paper unpacks the planning process into its component parts: model, process, technique, and goals—the “good thing”. The paper advances the concept that planning, policy-making, and organizational restructuring can be analyzed under the same framework. Each of the four components is described and reductionist examples are presented to clarify the intention and to illustrate the technique that the transport analyst teams employ in their work. The examples cover both successes and failures. They point toward the enormous scientific task ahead for planning to become meaningful and relevant to the problems of today. Finally, in the frame of the willingness to pay, the paper puts forward a case for an institutional framework for a financially autonomous road administration. Similarly organized, administered, and managed entities are relevant also for other transport modes.

How do people respond to congestion mitigation policies? A multivariate probit model of the individual consideration of three travel-related strategy bundles

This study explores the relationships between adoption and consideration of three travel-related strategy bundles (travel maintaining/increasing, travel reducing, and major location/lifestyle change), linking them to a variety of explanatory variables. The data for this study are the responses to a fourteen-page survey returned by nearly 1,300 commuting workers living in three distinct San Francisco Bay area neighborhoods in May 1998. We first identified patterns of adoption and consideration among the bundles, using pairwise correlation tests. The test results indicate that those who have adopted coping strategies continue to seek for improvements across the spectrum of generalized cost, but perhaps most often repeating the consideration of a previously-adopted bundle. Furthermore, we developed a multivariate probit model for individuals’ simultaneous consideration of the three bundles. It is found that in addition to the previous adoption of the bundles, qualitative and quantitative Mobility-related variables, Travel Attitudes, Personality, Lifestyle, Travel Liking, and Sociodemographics significantly affect individual consideration of the strategy bundles. Overall, the results of this study give policy makers and planners insight into understanding the dynamic nature of individuals’ responses to travel-related strategies, as well as differences between the responses to congestion that are assumed by policy makers and those that are actually adopted by individuals.

Modelling daily activity program generation considering within-day and day-to-day dynamics in activity-travel behaviour

This paper presents a comprehensive econometric modelling framework for daily activity program generation. It is for day-specific activity program generations of a week-long time span. Activity types considered are 15 generic categories of non-skeletal and flexible activities. Under the daily time budget and non-negativity of participation rate constraints, the models predict optimal sets of frequencies of the activities under consideration (given the average duration of each activity type). The daily time budget considers at-home basic needs and night sleep activities together as a composite activity. The concept of composite activity ensures the dynamics and continuity of time allocation and activity/travel behaviour by encapsulating altogether the activity types that are not of our direct interest in travel demand modelling. Workers’ total working hours (skeletal activity and not a part of the non-skeletal activity time budget) are considered as a variable in the models to accommodate the scheduling effects inside the generation model of non-skeletal activities. Incorporation of previous day’s total executed activities as variables introduces day-to-day dynamics into the activity program generation models. The possibility of zero frequency of any specific activity under consideration is ensured by the Kuhn-Tucker optimality conditions used for formulating the model structure. Models use the concept of random utility maximization approach to derive activity program set. Estimations of the empirical models are done using the 2002–2003 CHASE survey data set collected in Toronto.

Identifying peer states for transportation system evaluation &; policy analyses

The majority of comparisons between state transportation systems do not control for characteristics that may vary greatly between states (e.g., vehicle miles traveled). A shortcoming of such analyses is that a state’s individual characteristics can be highly influential in determining how transportation policy is set and funds are spent. The purpose of this paper is to extend previous efforts to create groups of similar peer states by developing a new methodological framework that incorporates demographic, temporal, and locational variability into the peer group delineations. We collected historical data for 42 variables on transportation infrastructure, population, economy, growth, topography and weather. To examine trends before and after the passage of ISTEA we gathered data over two time periods: 1985 through 1990 and 1995 through 2000. Using principal components analysis (PCA) we reduced variables into seven components, and then statistically clustered states into peer groups for each time period based on the components and the remaining variables. We identified a range of cluster solutions and demonstrate how cluster statistics help to describe the contextual basis behind the peer grouping. The results of this study are to provide government agencies, researchers and the public with a systematic methodological framework for identifying peer states that reflect similar attributes contributing to the development and maintenance of state transportation systems.

Curbing automobile use for sustainable transportation: analysis of mode choice on short home-based trips

This paper analyzes transportation mode choice for short home-based trips using a 1999 activity survey from the Puget Sound region of Washington State, U.S.A. Short trips are defined as those within the 95th percentile walking distance in the data, here 1.40 miles (2.25 km). The mean walking distance was 0.4 miles (0.6 km). The mode distribution was automobile (75%), walk (23%), bicycle (1%), and bus (1%). Walk and bicycle are found less likely as the individual’s age increases. People are more likely to drive if they can or are accustomed to. People in multi-person families are less likely to walk or use bus, especially families with children. An environment that attracts people’s interest and provides activity opportunities encourages people to walk on short trips. Influencing people’s choice of transport mode on short trips should be an important part of efforts encouraging the use of non-automobile alternatives.