Kevin F. Hulme

Frequency-dependent power output and skeletal muscle design

Cyclically contracting muscles provide power for a variety of processes including locomotion, pumping blood, respiration, and sound production. In the current study, we apply a computational model derived from force-velocity relationships to explore how sustained power output is systematically affected by shortening velocity, operational frequency, and strain amplitude. Our results demonstrate that patterns of frequency dependent power output are based on a precise balance between a muscles intrinsic shortening velocity and strain amplitude. We discuss the implications of this constraint for skeletal muscle design, and then explore implications for physiological processes based on cyclical muscle contraction. One such process is animal locomotion, where musculoskeletal systems make use of resonant properties to reduce the amount of metabolic energy used for running, swimming, or flying. We propose that skeletal muscle phenotype is tuned to this operational frequency, since each muscle has a limited range of frequencies at which power can be produced efficiently. This principle also has important implications for our understanding muscle plasticity, because skeletal muscles are capable of altering their active contractile properties in response to a number of different stimuli. We discuss the possibility that muscles are dynamically tuned to match the resonant properties of the entire musculoskeletal system.

Integrated Traffic-Driving-Networking Simulator for the Design of Connected Vehicle Applications: Eco-Signal Case Study

This article first develops an integrated traffic-driving-networking simulator (ITDNS) intended for the design and evaluation of cyber transportation systems (CTS) and connected vehicle (CV) applications. The ITDNS allows a human driver to control a subject vehicle, in a virtual environment, that is capable of communicating with other vehicles and the infrastructure with CTS messages. The challenges associated with the integration of the three simulators, and how those challenges were overcome, are discussed. As an application example, an eco-signal system, which recommends the approach speed for vehicles approaching the intersection so as to minimize fuel consumption and emissions, was implemented in the ITDNS. Test drivers were then asked to virtually drive through a signalized corridor twice, one time with the eco-signal system in place and another without the system. Thanks to the human-in-the-loop component of ITDNS, the research was able to evaluate the likely benefits of the eco-signal system, while accounting for the response of human drivers to the recommended speed profiles. Moreover, the study compared the energy consumption and emission production rates of human-controlled vehicles’ approach trajectories to the rates associated with “idealistic” trajectories that may be attainable via vehicle automation. With respect to ITDNS, the study demonstrates the unique advantages of the simulator and the broad range of applications it can address. Regarding the eco-signal application example, preliminary results demonstrate the potential of the concept to result in tangible reductions of around 9% for energy consumption, 18% for carbon monoxide, and 25% for nitrogen oxides emissions. Moreover, the application eliminated hard accelerations and decelerations maneuvers, and thus may have an additional positive safety impact.

Towards efficient vacant taxis Cruising Guidance

Different from the conventional operation mode in existing taxi dispatch systems, in this paper, we envision a new cyber-technology enabled taxi dispatch system which can efficiently provide vacant taxis with cruising route suggestions, not to respond to any specific pick-up request but instead, hoping to find prospective customers (such system is also complementary to the conventional operation mode). We address the Taxi Cruising Guidance (TCG) problem with the objective being to minimize the Global Vacant Rate (GVR), which is defined as the ratio of traveling miles with no passenger onboard, to the total traveling miles in a given time period. We propose a number of heuristic solutions and conduct comprehensive performance evaluations based on large-scale simulations. A case study is also presented by utilizing real traces collected from taxis in the city of Shanghai. As part of our research, we leverage a well-known microscopic traffic simulator (called TRANSIMS) to demonstrate that the application of TCG is also beneficial to traffic management.

Experiential learning in vehicle dynamics education via motion simulation and interactive gaming

Creating active, student-centered learning situations in postsecondary education is an ongoing challenge for engineering educators. Contemporary students familiar with visually engaging and fast-paced games can find traditional classroom methods of lecture and guided laboratory experiments limiting. This paper presents a methodology that incorporates driving simulation, motion simulation, and educational practices into an engaging, gaming-inspired simulation framework for a vehicle dynamics curriculum. The approach is designed to promote active student participation in authentic engineering experiences that enhance learning about road vehicle dynamics. The paper presents the student use of physical simulation and large-scale visualization to discover the impact that design decisions have on vehicle design using a gaming interface. The approach is evaluated using two experiments incorporated into a sequence of two upper level mechanical engineering courses.

Efficacy of a family-focused intervention for young drivers with attention-deficit hyperactivity disorder.

OBJECTIVE Teenage drivers diagnosed with attention-deficit/hyperactivity disorder (ADHD) are at significant risk for negative driving outcomes related to morbidity and mortality. However, there are few viable psychosocial treatments for teens with ADHD and none focus on the key functional area of driving. The Supporting the Effective Entry to the Roadway (STEER) program was evaluated in a clinical trial to investigate whether it improved family functioning as a proximal outcome and driving behavior as a distal outcome. METHOD One hundred seventy-two teenagers with ADHD, combined type, were randomly assigned to STEER or a driver education driver practice program (DEDP). RESULTS Relative to parents in the DEDP condition, parents in STEER were observed to be less negative at posttreatment and 6-month follow-up but not at 12-month follow-up, and there were no significant differences for observed positive parenting. Relative to teens in the DEDP condition, teens in STEER reported lower levels of risky driving behaviors at posttreatment and 6-month follow-up, but not at 12-month follow-up. Groups did not differ on objective observations of risky driving or citations/accidents. CONCLUSIONS The STEER program for novice drivers with ADHD was effective in reducing observations of negative parenting behavior and teen self-reports of risky driving relative to DEDP; groups did not significantly differ on observations of positive parenting or driving behaviors. (PsycINFO Database Record

Vehicle speed control algorithms for eco-driving

Given the rise in fuel prices and the harmful environmental consequences of excessive fuel consumption, we address a new problem in eco-driving, which examines how the upcoming V2V/V2I technology can be harnessed to improve fuel-efficiency. Unlike most of the existing studies in this area where the focus of control is on infrastructure side (i.e., signal timing plans), we present a new approach to eco-speed control at a microscopic level. We use a concept of platoon of vehicles to reduce fuel consumption in a journey covering multiple intersections in a multiple vehicle setting. Three heuristic algorithms are proposed and numerical results from simulations are also presented.

Simulation-Based Testing and Evaluation Tools for Transportation Cyber–Physical Systems

Transportation cyber-physical systems (TCPSs) require simulation-based testing and evaluation due to the prohibitive cost of building realistic test beds. Given the transdisciplinary nature of TCPSs, various simulation models and frameworks have been proposed in civil engineering, computer science, and related fields. Traditionally, researchers in different areas have developed their own set of simulation tools, which provide limited capability for TCPS research. In recent years, we have witnessed a growing interest of combining two or more features of traditional simulators to capture the unique characteristics of TCPSs. In this paper, we describe several mainstream simulation models used in transportation, communication, and human-factor studies in TCPS research. Moreover, we present our unique design and implementation of an integrated traffic-driving-network simulator (ITDNS). Finally, we discuss future enhancements that will promote best simulation practices for TCPS research.

Integrated Traffic-Driving-Networking Simulator: A Unique RaD Tool for Connected Vehicles

This paper describes on-going research aimed at developing a 3-in-1 integrated traffic-driving-networking simulator (ITDNS) for the design and evaluation of Cyber Transportation Systems (CTS) and Connected Vehicle (CV) applications. This unique simulator allows a human driver to control a subject vehicle in a virtual environment, this vehicle is capable of communicating with other vehicles and the infrastructure via CTS messages. The challenges associated with the integration of the three simulators, and how those challenges were overcome, are discussed.

Addressing the Safety of Transportation Cyber-Physical Systems: Development and Validation of a Verbal Warning Utility Scale for Intelligent Transportation Systems

As an important application of Cyber-Physical Systems (CPS), advances in intelligent transportation systems (ITS) improve driving safety by informing drivers of hazards with warnings in advance. The evaluation of the warning effectiveness is an important issue in facilitating communication of ITS. The goal of the present study was to develop a scale to evaluate the warning utility, namely, the effectiveness of a warning in preventing accidents in general. A driving simulator study was conducted to validate the Verbal Warning Utility Scale (VWUS) in a simulated driving environment. The reliability analysis indicated a good split-half reliability for the VWUS with a Spearman-Brown Coefficient of 0.873. The predictive validity of VWUS in measuring the effectiveness of the verbal warnings was verified by the significant prediction of safety benefits indicated by variables, including reduced kinetic energy and collision rate. Compared to conducting experimental studies, this scale provides a simpler way to evaluate overall utility of verbal warnings in communicating associated hazards in intelligent transportation systems. This scale can be further applied to improve the design of warnings of ITS in order to improve transportation safety. The applications of the scale in nonverbal warning situations and limitations of the current scale are also discussed.

Emerging Applications for Cyber Transportation Systems

Recent advances in connected vehicles and autonomous driving are going to change the face of ground transportation as we know it. This paper describes the design and evaluation of several emerging applications for such a cyber transportation system (CTS). These applications have been designed using holistic approaches, which consider the unique roles played by the human drivers, the transportation system, and the communication network. They can improve driver safety and provide on-road infotainment. They can also improve transportation operations and efficiency, thereby benefiting travelers and attracting investment from both government agencies and private businesses to deploy infrastructures and bootstrap the evolutionary process of CTS.