Path Planning with Time Windows for Multiple UAVs Based on Gray Wolf Algorithm

The Gray Wolf (GWO) algorithm aims to address the path planning problem of multiple UAVs, and the scene setting is mainly to avoid threats, meet the constraints of UAVs themselves and avoid obstacles between UAVs. The scene setting is relatively simple. To address such problems, the problem of time windows is considered in this paper, so that the UAV can arrive at the same time, and the Gray Wolf algorithm is used to optimize the problem. Finally, the experimental results verify that the proposed method can plan a safe flight path in the process of multi-UAV flight and reach the goal point at the same time. The mean error of flight time between UAVs of the GWO is 0.213, which is superior to PSO (0.382), AFO (0.315) and GA (0.825).

Variable Neighborhood Search for Multi-Cycle Medical Waste Recycling Vehicle Routing Problem with Time Windows

BACKGROUND

Improper disposal of urban medical waste is likely to cause a series of neglective impacts. Therefore, we have to consider how to improve the efficiency of urban medical waste recycling and lowering carbon emissions when facing disposal.

METHODS

This paper considers the multi-cycle medical waste recycling vehicle routing problem with time windows for preventing and reducing the risk of medical waste transportation. First, a mixed-integer linear programming model is formulated to minimize the total cost consisting of the vehicle dispatch cost and the transportation costs. In addition, an improved neighborhood search algorithm is designed for handling large-sized problems. In the algorithm, the initial solution is constructed using the Clarke-Wright algorithm in the first stage, and the variable neighborhood search algorithm with a simulated annealing strategy is introduced for exploring a better solution in the second stage.

RESULTS

The computational results demonstrate the performance of the suggested algorithm. In addition, the total cost of recycling in the periodic strategy is lower than with the single-cycle strategy.

CONCLUSIONS

The proposed model and algorithm have the management improvement value of the studied medical waste recycling vehicle routing problem.

Vessel Scheduling Optimization Model Based on Variable Speed in a Seaport with One-Way Navigation Channel

To improve the efficiency of in-wharf vessels and out-wharf vessels in seaports, taking into account the characteristics of vessel speeds that are not fixed, a vessel scheduling method with whole voyage constraints is proposed. Based on multi-time constraints, the concept of a minimum safety time interval (MSTI) is clarified to make the mathematical formula more compact and easier to understand. Combining the time window concept, a calculation method for the navigable time window constrained by tidal height and drafts for vessels is proposed. In addition, the nonlinear global constraint problem is converted into a linear problem discretely. With the minimum average waiting time as the goal, the genetic algorithm (GA) is designed to optimize the reformulated vessel scheduling problem (VSP). The scheduling methods under different priorities, such as the first-in-first-out principle, the largest-draft-vessel-first-service principle, and the random service principle are compared and analyzed experimentally with the simulation data. The results indicate that the reformulated and simplified VSP model has a smaller relative error compared with the general priority scheduling rules and is versatile, can effectively improve the efficiency of vessel optimization scheduling, and can ensure traffic safety.

Early reduced behavioral activity induced by large strokes affects the efficiency of enriched environment in rats

The majority of stroke patients develop post-stroke fatigue, a symptom which impairs motivation and diminishes the success of rehabilitative interventions. We show that large cortical strokes acutely reduce activity levels in rats for 1-2 weeks as a physiological response paralleled by signs of systemic inflammation. Rats were exposed early (1-2 weeks) or late (3-4 weeks after stroke) to an individually monitored enriched environment to stimulate self-controlled high-intensity sensorimotor training. A group of animals received Anti-Nogo antibodies for the first two weeks after stroke, a neuronal growth promoting immunotherapy already in clinical trials. Early exposure to the enriched environment resulted in poor outcome: Training intensity was correlated to enhanced systemic inflammation and functional impairment. In contrast, animals starting intense sensorimotor training two weeks after stroke preceded by the immunotherapy revealed better recovery with functional outcome positively correlated to the training intensity and the extent of re-innervation of the stroke denervated cervical hemi-cord. Our results suggest stroke-induced fatigue as a biological purposeful reaction of the organism during neuronal remodeling, enabling new circuit formation which will then be stabilized or pruned in the subsequent rehabilitative training phase. However, intense training too early may lead to wrong connections and is thus less effective.

Pharmacologically pertinent period of effect (PPPE)

Background

The period of time during which a patient is exposed to a drug does not necessarily correspond to the period during which the drug produces the adverse effect under consideration. We propose the term Pharmacologically pertinent period of effect (PPPE) to address this time window. We explored the PPPE in light of the rofecoxib saga.

Methods

We identified the observational database studies of rofecoxib at doses 25 and 50 mg daily and thromboembolic events. We also obtained the Kaplan‐Meier curves of Vioxx Gastrointestinal Outcomes Research trial (VIGOR) and Adenomatous Polyp Prevention on Vioxx (APPROVE) trials.

Results

We found seven observational studies with nine analyses. All the studies only looked at current exposure. At the dose of 25 mg, only three of nine analyses were barely statistically significant. At the dose of 50 mg, the risk ratios were much higher. The visual inspection of the Kaplan‐Meier curves shows that in the APPROVE trial (25 mg), the placebo and rofecoxib curves start separating to become statistically significantly different only after 36 months. In contrast the VIGOR (50 mg), curves start separating very early and the divergence increases after 8 months.

Discussion

The 50 mg observational studies, looking at current exposure, correctively identified the almost immediate increase in risk evident in the VIGOR Kaplan‐Meier curves. The absence of an immediate increase in risk shown by the APPROVE trial was also correctively identified by most observational 25 mg studies. To our knowledge no observational study was done on the long‐term cardiac toxicity of the 25‐mg dose. It would thus appear that the two doses of rofecoxib have different PPPEs.

Developing an applied algorithm for multi-trip vehicle routing problem with time windows in urban waste collection: A case study

This paper studies a multi-trip vehicle routing problem with time windows specifically related to urban waste collection. Urban waste collection is one of the municipal activities with large costs and has many practical difficulties. In other words, waste collection and disposal is a costly task due to high operating expenses (fuel, maintenance, recycling, manpower, etc.) and small improvements in this field can result in tremendous savings on municipal expenditure. In the raised problem, the goal is to minimize total cost including traversing cost, vehicle employment cost, and exit penalty from permissible time windows. In this problem, the waste is deposited at the points indicating the demand nodes, in which each demand shows the volume of generated waste. Considering multiple trips for vehicles and time windows are the most critical features of the problem, so that the priorities of serving some specific places such as hospitals can be observed. Since vehicle routing problems (VRP) belongs to NP-hard problems, an efficient simulated annealing (SA) is proposed to solve the problem. The computational results show that our proposed algorithm has a great performance in a short computational time in comparison with the CPLEX solver. Finally, in order to demonstrate the applicability of the model, a case study is analyzed in Iran, and the optimal policies are presented.

Rethinking the Clinically Based Thresholds of TransCelerate BioPharma for Risk-Based Monitoring

BACKGROUND

The quality of data from clinical trials has received a great deal of attention in recent years. Of central importance is the need to protect the well-being of study participants and maintain the integrity of final analysis results. However, traditional approaches to assess data quality have come under increased scrutiny as providing little benefit for the substantial cost. Numerous regulatory guidance documents and industry position papers have described risk-based approaches to identify quality and safety issues. In particular, the position paper of TransCelerate BioPharma recommends defining risk thresholds to assess safety and quality risks based on past clinical experience. This exercise can be extremely time-consuming, and the resulting thresholds may only be relevant to a particular therapeutic area, patient or clinical site population. In addition, predefined thresholds cannot account for safety or quality issues where the underlying rate of observing a particular problem may change over the course of a clinical trial, and often do not consider varying patient exposure.

METHODS

In this manuscript, we appropriate rules commonly utilized for funnel plots to define a traffic-light system for risk indicators based on statistical criteria that consider the duration of patient follow-up. Further, we describe how these methods can be adapted to assess changing risk over time. Finally, we illustrate numerous graphical approaches to summarize and communicate risk, and discuss hybrid clinical-statistical approaches to allow for the assessment of risk at sites with low patient enrollment.

RESULTS

We illustrate the aforementioned methodologies for a clinical trial in patients with schizophrenia.

CONCLUSIONS

Funnel plots are a flexible graphical technique that can form the basis for a risk-based strategy to assess data integrity, while considering site sample size, patient exposure, and changing risk across time.

Childhood leukemia in the vicinity of the Geesthacht nuclear establishments near Hamburg, Germany

BACKGROUND

During 1990-1991 a childhood leukemia cluster was observed in the sparsely populated region surrounding two nuclear establishments southeast of Hamburg, Germany. Since then, several new cases have been reported. Recently a possible accidental release of radionuclides in 1986 was hypothesized.

OBJECTIVE

The objective of this study was to analyze the childhood leukemia incidence in this area since 1990.

METHODS

All incident cases (< 15 years of age) were ascertained during 1990-2005 within a 5-km radius of the Krümmel nuclear power plant. We derived standardized incidence ratios (SIRs) using county and national leukemia incidence rates as referents. We stratified analyses by calendar period and attained age, and by subdividing the study region into areas north versus south of the Elbe river.

RESULTS

Fourteen cases were ascertained in the study area, whereas 4.0 were expected based on national referent rates [1990-2005: SIR = 3.5; 95% confidence interval (CI), 1.9-5.9]. The excess was not confined to the early 1990s; for the more recent time period 1999-2005, the SIR is still elevated (SIR = 2.7; 95% CI, 0.9-6.2). SIRs of greatest magnitude were observed for children 0-4 years of age (SIR = 4.9; 95% CI, 2.4-9.0) and for residents south of the Elbe (SIR = 7.5; 95% CI, 2.8-16.4).

CONCLUSIONS

The incidence in this region is significantly higher than the childhood leukemia incidence for Germany as a whole. To date, no unique hazards have been identified in this population. The fact that the elevated rates have persisted in this community for > 15 years warrants further investigation.