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Cooperative Adaptive Cruise Control (CACC), as an advanced version of adaptive cruise control (ACC), automates brake and engine controls based on the information received from wireless V2V communications and remote sensors, enabling smaller vehicle-following time gaps. It can improve the safety of vehicle platooning and increase fuel savings. As an extension of our previous investigation of truck drivers' acceptance of CACC, this case study investigates factors affecting the use of CACC for truck platooning. Nine commercial fleet drivers were recruited to operate two following trucks in a CACC-enabled string on freeways in Northern California. We analyzed the usage of CACC time gaps and its correlation with truck drivers' stated preferences for these time gaps, and we found that the highest preferred Gap 3 (1.2 s) was used the most. Moreover, a Bayesian regression model was built to show that truck drivers are more likely to disengage CACC when driving in low-speed traffic or on downgrades where this CACC could not provide sufficient braking. In high-speed traffic or on upgrades, truck drivers are more likely to engage CACC, particularly at Gap 3. Truck position, however, does not affect truck drivers' time gap selection. The findings encourage the adoption of CACC in the trucking industry through implementing driver-preferred time gaps and responsive braking systems, and operating on routes with minimal interference to truck speeds. [ABSTRACT FROM AUTHOR]

Recent studies have shown that positive impact of Cooperative Adaptive Cruise Control (CACC) can only be guaranteed as market penetration rate increases. Removing the string homogeneity constraint is essential to encourage widespread adoption. In this work, a hierarchical architecture is proposed to enable CACC on vehicles with not only mixed dynamics but also different powertrain types. A low-level layer deals with the vehicle and powertrain dynamics to provide accurate and consistent reference speed tracking response. The high-level layer uses: (1) a Linear Parameter Varying feedback system to provide loop stability, robustness and enforce a variable time gap policy and (2) a feedforward system that processes Vehicle-to-Vehicle information to enhance string stability and response bandwidth, by dealing with the string heterogeneity. A gap management strategy is built on top of the CACC architecture to handle gap setting changes or cut-in/out situations, via a dynamics constrained time gap trajectory planning algorithm. The proposed work has been designed, developed and validated on three different real passenger vehicles on public highways and test tracks, showing the potential of the proposed algorithm to enable robust string stable CACC, despite the different dynamics and powertrains considered. [ABSTRACT FROM AUTHOR]

Quantifying the effect of Cooperative Adaptive Cruise Control (CACC) on traffic mobility and vehicle fuel consumption has been a challenge because it requires a modeling framework that depicts the interactions among manually driven vehicles and CACC vehicles in the complex multilane traffic stream. This study adopted a state-of-the-art traffic flow modeling framework to explore the impacts of CACC on vehicle fuel efficiency in mixed traffic. The analyses at a freeway merge bottleneck indicated that the CACC string operation resulted in a maximum of 20% reduction in energy consumption compared to the human driver only case. At 100% market penetration, CACC equipped vehicles consume 50% less fuel than adaptive cruise control (ACC) vehicles without vehicle-to-vehicle (V2V) communication and cooperation. This implied the importance of incorporating the V2V cooperation component into the automated speed control system. In addition, the CACC string operation could substantially improve freeway capacity without degrading the vehicle fuel efficiency. At 100% CACC market penetration, the capacity increased by 49% while the vehicle fuel consumption rate per vehicle mile traveled remained the same as the rate observed in the human driver only case. At lower CACC market penetrations, the vehicle fuel efficiency could be improved via using the dedicated CACC lane or implementing wireless connectivity on the manually driven vehicles. In the 40% CACC case, those strategies brought about 15% to 19% capacity increase without decreasing vehicle fuel efficiency. Those results highlighted the necessity of deploying CACC-specific operation strategies under lower CACC market penetrations. [ABSTRACT FROM AUTHOR]

To facilitate the cell-based experiment for pulsed electromagnetic field biological effect study, a novel TEM-cell-integrated CO2 incubator was developed. The integrated experimental system could simultaneously meet the requirement of standard cell culture condition and the various Transient Electromagnetic Field (TEF) exposure, which made it possible to study the relationship between different electromagnetic pulse exposure and the cellular responses in a reliable way. During the research, a comparison experiment was carried out to evaluate the necessity of the integrated incubator system: firstly, two different types of cell lines, which are the human prostate cancer cell line (PC3) and the pancreatic β cell line (MIN6) were chosen and exposed in the TEM-cell which located in the open area and the integrated system, respectively, with the same EFT radiation conditions; then, the cells' viability, the cellular ROS level and the mitochondrial membrane potential (MMP) were detected, respectively. The results showed that in the same parameter of the EFT radiation, the processes of the cells had a significant difference and even opposite in the incubator and open area, and all the results could be reproducible. The phenomenon indicated the stability of the TEM-cell-integrated CO2 incubator, and also demonstrated the necessity to strictly control the cell culture condition when carrying out the precise mechanism study of the TEF bioresponse at the cellular levels. [ABSTRACT FROM AUTHOR]

Cooperative Adaptive Cruise Control (CACC) allows vehicles to exchange real-time operational information wirelessly, enabling vehicles to travel in strings with shorter than normal time gaps between adjacent vehicles and ultimately increasing the freeway capacity. This study is intended to investigate the impact of CACC vehicle string operation on the capacity of multilane freeway merge bottlenecks, commonly found at on-ramp merging areas on urban freeways. Simulation experiments were conducted using CACC car-following models derived from field test data, together with lane-changing models of CACC vehicles and manually driven vehicles, as well as a maximum CACC string length and inter-string time gap constraint. Simulation results reveal that the freeway capacity increases quadratically as the CACC market penetration increases, with a maximum value of 3080 veh/hr/lane at 100% market penetration. The disturbance from the on-ramp traffic causes the merge bottleneck and can reduce the freeway capacity by up to 13% but the bottleneck capacity still increases in a quadratic pattern as CACC market penetration becomes larger. The findings suggest that there is a need to implement advanced merging assistance systems with CACC at merge bottlenecks for achieving the capacity improvement comparable with the observations at homogeneous freeway segments. [ABSTRACT FROM AUTHOR]

Objective: Efforts have been made by tissue engineers to create a permissive environment for neural regeneration, and to enhance the efficiency of neural stem cell (NSC) transplantation. However, to acquire sufficient number of seed cells on the material appears to be the main obstacle to constructing functional transplantable NSC-biomaterial complexes. A culture system has been optimized in the current study to maintain the specific characteristics of NSCs/neural progenitor cells (NPCs) on the material and achieve sustaining increased multipotent seed cells. Methods: The PHBHHx film was selected as biomaterial and the surface was firstly modified with NaOH treatment. The NSCs/NPCs isolated from the cerebral cortex of rat embryos were cultured on the treated PHBHHx films in growth medium containing 1%, 5%, and 10% fetal bovine serum (FBS). Then the attachment, survival, proliferation, and differentiation of NSCs/NPCs were assessed. Results: NaOH treatment significantly increased the hydrophilicity of PHBHHx and enhanced NSCs/NPCs attachment. On the treated PHBHHx film, NSCs/NPCs survived well and actively proliferated in the medium containing 1% FBS. After 7-14 days in culture, approximately two-thirds of cells remained as nestin and Sox2 positive NSCs/NPCs. However, in the medium containing 5% and 10% FBS, NSCs/NPCs proliferation was reduced and differentiation, particularly glial differentiation was significantly promoted. Conclusion: Growth medium containing low concentration of FBS is favorable for maintaining the characteristics, in terms of self-renewal and multiple differentiation, of NSCs/NPCs on NaOH-treated PHBHHx films. This could be a useful method to construct functional transplantable NSCs/NPCs-biomaterial complex. [ABSTRACT FROM AUTHOR]

The paper presents a real-time implementation of a general merging algorithm for automated highway systems. A merging control problem is proposed first. A real-time algorithm, which is used to calculate a smooth reference speed trajectory for the merging vehicle based on the speed of the main lane vehicle. This algorithm can also be applied even when the main lane vehicles change speed. To make the algorithm adapt to different road layouts and to increase safety, a concept of virtual platooning is proposed. It effectively shifts the time of platoon formation forward prior to the start of real merging. Aspects closely related to real-time implementation are discussed, such as the controller adopted, the use of magnetometer based distance measurement and information passing by communication form main lane vehicles. Test results are presented and briefly analyzed. [ABSTRACT FROM AUTHOR]

This paper considers longitudinal control of automated vehicle merging in a mathematical approach for automated highway systems. Merging manoeuvre is defined as one vehicle in the merging lane to be inserted in the middle between two vehicles in the main lane at fixed merging point which is the intersection of those two lanes. The main lane vehicles can change speed. To achieve this, the merging vehicle must properly adjust its speed and acceleration such that it reaches the merging point at the right time with the same speed and acceleration as the main lane vehicles. This problem is a little similar to but different from the well-known missile interception problem. The longitudinal control problem is proposed for different road layouts, based on which a unified mathematical model is established. Then a new concept, virtual platooning, is introduced, which effectively avoids a two-point boundary value problem. Based on this concept, an analytic solution with mathematical proof is provided. It is also discretized as a recursive algorithm for real-time use. A dynamic real-time simulation is published at PATH website. This algorithm has been successfully implemented with automated cars. [ABSTRACT FROM AUTHOR]

A newly developed dynamic sliding mode control technique for multiple input systems is shown to be useful in the control of nonlinear, non-minimum phase systems where the zero dynamics have no finite escape time. The system may not be dynamic feedback linearizable. To achieve asymptotic performance, unbounded control may be necessary as determined by the zero dynamics. As long as the growth rate of the zero dynamics is no more than exponential, ultimate bounded performance can be achieved with finite control effort. Lagrange stability analysis of the closed-loop system resulting from the proposed variable structure scheme is performed. Essentially a thin layer is introduced around the sliding surface. Outside the layer, the sliding mode controller is used; inside the layer, the controller is designed to asymptotically (exponentially) stabilize the dynamic compensator. It is shown that there is a trade-off between control performance and control effort. The method is illustrated by the control of the Inverted Double Pendulum which is not dynamic-feedback linearizable and is non-minimum phase and thus constitutes a testing example for the proposed scheme. [ABSTRACT FROM AUTHOR]

Robustness of static sliding mode control based on affine non-linear state space models in regular form is considered. This is necessary because the stability of non-linear systems is usually a local property which can be destroyed by an additive uncertainty. Thus the uncertainty should be appropriately structured. A cone bounded uncertainty structure is assumed in this paper. In general, when a regular form is used to design a static sliding mode control, only matched uncertainty can be expelled. For the stability of the closed-loop system, a minimum phase assumption is necessary. It is shown that the sliding manifold is equivalent to the manifold determined by the zero dynamics and the minimum phase assumption relates to the compactness of the sliding manifold in the ideal sliding mode. It is also shown that the two phase separability, i.e. reaching mode and ideal sliding mode, which holds for linear systems, does not hold generally for non-linear systems. A pertinent example is given. [ABSTRACT FROM AUTHOR]

Discusses the output feedback stabilization of SISO nonlinear systems through dynamic sliding modes. Background on the sliding mode control and output feedback control; Semi-high gain observer into the closed-loop systems resulting from dynamic sliding mode control; Stability of the closed-loop system through the Lyapunov approach.