Level 3 autonomous vehicles require conditional autonomous driving in which autonomous and manual driving are alternately performed; whether the driver can resume manual driving within a limited time ...should be examined. This study investigates whether the demographics and subjective driving tendencies of drivers affect the take‐over performance. We measured and analyzed the reengagement and stabilization time after a take‐over request from the autonomous driving system to manual driving using a vehicle simulator that supports the driver's take‐over mechanism. We discovered that the driver's reengagement and stabilization time correlated with the speeding and wild driving tendency as well as driving workload questionnaires. To verify the efficiency of subjective questionnaire information, we tested whether the driver with slow or fast reengagement and stabilization time can be detected based on machine learning techniques and obtained results. We expect to apply these results to training programs for autonomous vehicles' users and personalized human–vehicle interfaces for future autonomous vehicles.
A new coordination control is developed in this paper for multiple non-holonomic robots in a competitive manner for target tracking with limited communications. In this proposed control approach, ...only winners of the competition are allocated the task and activated to move towards the target. A distributed coordination model is proposed and its stability is proved in theory. Inspired by the besieging behaviors in social animals for predating, an effective strategy to handle the situation with higher target speed than trackers is also proposed and verified to be extraordinarily effective.
Background and aims
The province of British Columbia (BC) Canada has experienced a rapid increase in illicit drug overdoses and deaths during the last 4 years, with a provincial emergency declared in ...April 2016. These deaths have been driven primarily by the introduction of synthetic opioids into the illicit opioid supply. This study aimed to measure the combined impact of large‐scale opioid overdose interventions implemented in BC between April 2016 and December 2017 on the number of deaths averted.
Design
We expanded on the mathematical modelling methodology of our previous study to construct a Bayesian hierarchical latent Markov process model to estimate monthly overdose and overdose‐death risk, along with the impact of interventions.
Setting and Cases
Overdose events and overdose‐related deaths in BC from January 2012 to December 2017.
Interventions
The interventions considered were take‐home naloxone kits, overdose prevention/supervised consumption sites and opioid agonist therapy
Measurements
Counterfactual simulations were performed with the fitted model to estimate the number of death events averted for each intervention and in combination.
Findings
Between April 2016 and December 2017, BC observed 2177 overdose deaths (77% fentanyl‐detected). During the same period, an estimated 3030 (2900–3240) death events were averted by all interventions combined. In isolation, 1580 (1480–1740) were averted by take‐home naloxone, 230 (160–350) by overdose prevention services and 590 (510–720) were averted by opioid agonist therapy.
Conclusions
A combined intervention approach has been effective in averting overdose deaths during British Columbia's opioid overdose crisis in the period since declaration of a public health emergency (April 2016–December 2017). However, the absolute numbers of overdose deaths have not changed.
We study the impact of product recovery on a firm's product quality choice, where quality is defined as an observable performance measure that increases a consumer's valuation for the product. We ...consider three general forms of product recovery: (i) when product recovery reuses (after reprocessing) quality inducing components or material (e.g., remanufacturing), (ii) when product recovery does not reuse quality inducing components or material but it is overall profitable (e.g., cell phone recycling), and (iii) when product recovery is costly (but mandated by legislation, e.g., recycling of small appliances in the European Union). Using a stylized economic model, we show that the form of product recovery, recovery cost structure, and the presence of product take‐back legislation play an important role in quality choice. Generally speaking, product recovery increases the firm's quality choice, except for some instances of recovery form (ii). In addition, we find that product take‐back legislation can lead to higher quality choice as opposed to voluntary take‐back. We further demonstrate that both the firm and the consumers benefit from recovery form (ii), while both are worse off with recovery form (iii). However, environmental implications of the three recovery modes differ from their impact on consumer surplus and firm profit. While recovery forms (i) and (iii) reduce consumption and increase environmental benefits, the same is not true with recovery form (ii), which can increase consumption, potentially resulting in higher environmental impact.
•A novel mechanical Power Take-off with compact design for wave energy converters.•Using Mechanical Motion Rectifier mechanism to improve the power absorption.•Dry lab bench test matched well with ...the theoretical analysis.•Achieved up to 81.2% of efficiency in dry lab test and 62.4% in wave tank test.
Power Take-off (PTO) is one of the most critical components in the field of ocean wave energy conversion. This paper introduces a novel compact mechanical PTO using a ball screw mechanism and a Mechanical Motion Rectifier (MMR) to improve the energy conversion performance. The proposed MMR PTO converts the bidirectional oscillatory motion of the ocean waves into the unidirectional rotation. The detailed design and working principle of the MMR PTO are explicitly explained. Dynamic analysis is presented for the three most important factors that influence the performance, including the equivalent mass, the equivalent damping, and the excitation frequency. The analytical relationship between these factors and the disengaged freewheeling motion caused by the MMR mechanism is derived, and the analytical solution is verified through dry lab testing. Experimental results in bench tests show that compared with the traditional linear PTO which uses the ball screw to drive the generator directly, the MMR PTO is more efficient because of the unique freewheeling motion, achieving a maximum 81.2% energy transfer efficiency. After integrating the prototyped PTO with a single-body point absorber type of wave energy converter, the testing in a water tank show that the MMR PTO can achieve total efficiency up to 62.4%, showing promising potential for real applications.
The article's proposal refers to a new concept of wave energy converter (WEC), in which the power take-off (PTO) is combined with the mechanical and hydrostatic transmission. Here, the wave energy is ...absorbed by turning the two-way movement of an incident wave into the one-way rotation of a hydraulic pump which drives a high-pressure (HP) hydraulic circuit. Electricity is generated using a rotating generator which is driven by an HP hydraulic circuit. First, the coupled PTO mechanism is presented to describe the working principle of the proposed WEC. Next, a mathematical model of the buoy connects generator system is shown to analyze the equipment’s performance subjected regular waves. And then, by using the theory of linear potential wave, the hydrodynamic forces acting on the semi-submerged floating buoy and an analytical model of the mechanical transmission coupled with the hydraulic transmission are modeled to investigate the motion of the rotary generator. An experimental Setup is performed to verify the analytical model. Based on the validated model, a structural optimization is calculated to bring the system to resonance condition. Then, a dry test is implemented to analyze the system’s performance. Some optimum parameters are determined and applied to the analytical model, which sends the signal to drive the actuator. As a result, the absorbed efficiency is increased significantly.
ABSTRACT
In the last two decades, many countries have enacted product take‐back legislation that holds manufacturers responsible for the collection and environmentally sound treatment of end‐of‐use ...products. In an industry regulated by such legislation, we consider a manufacturer that also sells remanufactured products under its brand name. Using a stylized model, we consider three levels of legislation: no take‐back legislation, legislation with collection targets, and legislation with collection and reuse targets. We characterize the optimal solution for the manufacturer and analyze how various levels of legislation affect manufacturing, remanufacturing, and collection decisions. First, we explore whether legislation with only collection targets causes an increase in remanufacturing levels, which is argued to be an environmentally friendlier option for end‐of‐use treatment than other options such as recycling. While increased remanufacturing alone is usually perceived as a favorable environmental outcome, if one considers the overall environmental impact of new and remanufactured products, this might not be the case. To study this issue, we model the environmental impact of the product following a life cycle analysis–based approach. We characterize the conditions under which increased remanufacturing due to take‐back legislation causes an increase in total environmental impact. Finally, we model the impact of legislation on consumer surplus and manufacturer profits and identify when total welfare goes down because of legislation.
Sea wave energy is being increasingly regarded in many countries as a major and promising resource. The paper deals with the development of wave energy utilization since the 1970s. Several topics are ...addressed: the characterization of the wave energy resource; theoretical background, with especial relevance to hydrodynamics of wave energy absorption and control; how a large range of devices kept being proposed and studied, and how such devices can be organized into classes; the conception, design, model-testing, construction and deployment into real sea of prototypes; and the development of specific equipment (air and water turbines, high-pressure hydraulics, linear electrical generators) and mooring systems.
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