Direct Allocation Method Research Articles

UAV Swarm Scheduling Method for Remote Sensing Observations during Emergency Scenarios

Recently, unmanned aerial vehicle (UAV) remote sensing has been widely used in emergency scenarios; the operating mode has transitioned from one UAV to multiple UAVs. However, the current multiple-UAV remote sensing mode is characterized by high labor costs and limited operational capabilities; meanwhile, there is no suitable UAV swarm scheduling method that can be applied to remote sensing in emergency scenarios. To solve these problems, this study proposes a UAV swarm scheduling method. Firstly, the tasks were formulated and decomposed according to the data requirements and the maximum flight range of a UAV; then, the task sets were decomposed according to the maximum flight range of the UAV swarm to form task subsets; finally, aiming at the shortest total flight range of the task subsets and to balance the flight ranges of each UAV, taking the complete execution of the tasks as the constraint, the task allocation model was constructed, and the model was solved via a particle swarm optimization algorithm to obtain the UAV swarm scheduling scheme. Compared with the direct allocation method and the manual scheduling methods, the results show that the proposed method has high usability and efficiency.

Optimal Control Allocation for AUVs with Through-body Thrusters

Developing multi-purpose AUV with through-body thrusters capable of undertaking both survey-style missions and low-speed interaction requires sophisticated thruster allocation algorithms. The paper presents the adaptive optimal allocation method. This method allows a smooth transition between different motion styles by exponentially decreasing through-body thrusters’ involvement according to their hydrodynamic model. The proposed method is compared with the prioritized direct allocation method. The simulation result of the control allocation for the AUV “MMT-300” propulsion system model is provided.

Take-Off Trajectory Optimization of Tilt-rotor Aircraft Based on Direct Allocation Method

During the take-off stage, the tilt-rotor aircraft’s actuator is redundant and difficult to control. In order to take off more quickly and safety reach horizontal flight state with less power consumption, the take-off trajectory is necessary to be optimized. this paper introduces the direct allocation method to optimize the take-off trajectory of tilt-rotor aircraft. Firstly, the dynamic model of the take-off stage of the tilt-rotor aircraft is established. According to the actual flight conditions, the constraints and the optimization objective function of the take-off process are established. Then, the entire take-off process is divided into several segments according to time, and the continuous optimal control problem is discretized into a nonlinear programming problem by using the direct allocation method. The state and control variables at each segment point and midpoint are taken for optimization. and then the optimized variables are fitted by the third-order Simpson method. Finally, GPOPS toolbox in MATLAB was used to solve the nonlinear programming problem. The simulation results show that the optimized take-off trajectory can well meet the boundary constraints, and its solutions are stable.

High-Level Disinfection of Otorhinolaryngology Clinical Instruments: An Evaluation of the Efficacy and Cost-effectiveness of Instrument Storage.

Objectives Despite increasing interest in individual instrument storage, risk of bacterial cross-contamination of otorhinolaryngology clinic instruments has not been assessed. This study is the first to determine the clinical efficacy and cost-effectiveness of standard high-level disinfection and clinic instrument storage. Methods To assess for cross-contamination, surveillance cultures of otorhinolaryngology clinic instruments subject to standard high-level disinfection and storage were obtained at the start and end of the outpatient clinical workday. Rate of microorganism recovery was compared with cultures of instruments stored in individual peel packs and control cultures of contaminated instruments. Based on historical clinic data, the direct allocation method of cost accounting was used to determine aggregate raw material cost and additional labor hours required to process and restock peel-packed instruments. Results Among 150 cultures of standard high-level disinfected and co-located clinic instruments, 3 positive bacterial cultures occurred; 100% of control cultures were positive for bacterial species ( P < .001). There was no statistical difference between surveillance cultures obtained before and after the clinic day. While there was also no significant difference in rate of contamination between peel-packed and co-located instruments, peel packing all instruments requires 6250 additional labor hours, and conservative analyses place the cost of individual semicritical instrument storage at $97,852.50 per year. Discussion With in vitro inoculation of >200 otorhinolaryngology clinic instruments, this study demonstrates that standard high-level disinfection and storage are equally efficacious to more time-consuming and expensive individual instrument storage protocols, such as peel packing, with regard to bacterial contamination. Implications for Practice Standard high-level disinfection and storage are equally effective to labor-intensive and costly individual instrument storage protocols.

Complexity control algorithm based on adaptive mode selection for interframe coding in high efficiency video coding

The latest high efficiency video coding (HEVC) standard significantly increases the encoding complexity for improving its coding efficiency. Due to the limited computational capability of handheld devices, complexity constrained video coding has drawn great attention in recent years. A complexity control algorithm based on adaptive mode selection is proposed for interframe coding in HEVC. Considering the direct proportionality between encoding time and computational complexity, the computational complexity is measured in terms of encoding time. First, complexity is mapped to a target in terms of prediction modes. Then, an adaptive mode selection algorithm is proposed for the mode decision process. Specifically, the optimal mode combination scheme that is chosen through offline statistics is developed at low complexity. If the complexity budget has not been used up, an adaptive mode sorting method is employed to further improve coding efficiency. The experimental results show that the proposed algorithm achieves a very large complexity control range (as low as 10%) for the HEVC encoder while maintaining good rate-distortion performance. For the lowdelayP condition, compared with the direct resource allocation method and the state-of-the-art method, an average gain of 0.63 and 0.17 dB in BDPSNR is observed for 18 sequences when the target complexity is around 40%.

Szívtranszplantáció és műszívkezelés költséghatékonysági elemzési modellje

Heart transplantation is a high priority project at Semmelweis University. In accordance with this, the funding of heart transplantation and mechanical circulatory support also constitutes an important issue. In this report, the authors discuss the creation of a framework with the purpose of comparing the cost-effectiveness of heart transplantation and artificial heart implantation. Our created framework includes the calculation of cost, using the direct allocation method, calculating the incremental cost-effectiveness ratio and creating a cost-effectiveness plane. Using our model, it is possible to compare the initial, perioperative and postoperative expenses of both the transplanted and the artificial heart groups. Our framework can possibly be used for the purposes of long term follow-up and with the inclusion of a sufficient number of patients, the creation of cost-effectiveness analyses and supporting strategic decision-making.

COST ANALYSIS OF EXPANDED PROGRAM ON IMMUNIZATION AT BASIS HEALTH LEVEL IN THUA THIEN HUE PROVINCE, VIETNAM

Background: In Vietnam, expanded program on immunization (EPI) has vaccinated freely 8 vaccines to children under one year old to protect from tuberculosis, diphtheria, pertussis, tetanus, hepatitis B, polio, measles and pneumonia/ meningitis caused by Hib. The study aims to 1) identify total cost and cost items of EPI at basis health level of Thua Thien Hue province within the first 6 months of the year 2014 and 2) estimate average cost of vaccine delivery per dose and cost per fully vaccinated child (FVC). Materials and method: This is a descriptive cross sectional study. Costs were analyzed on the basis of perspective of health service providers. A direct allocation method was used to estimate average cost of vaccine delivery per dose and cost per FVC. Data of the program within the first 6 months of the year 2014 was collected in provincial preventive medicine center, 3 district health centers and 9 CHCs in TT Hue province to estimate cost. The price of capital assets was adjusted by inflation with time and was annualized using a discount rate of 3%. One-way sensitivity analyses investigated the impact of cost items and wastage ratio on cost of vaccine delivery. Results: The total cost of EPI within 6 months in 9 CHCs was 452.947.417 VND (US$ 21.532) in which vaccine price shared the largest component cost (41.3%). The average cost per FVC was 456.059VND (US$ 21.68) that is higher than of US$ 15 per FVC only for 6 vaccines as recommendation of WHO. The cost was sensitive to wastage ratio of vaccines. Conclusion: The cost of US$ 21.68 per FVC preventing from 8 dangerous infected diseases found in this study is higher than that of threshold of WHO per FVC only for 6 vaccines of EPI in some developing countries. Key words: Expanded program on immunization, vaccine, cost items, basis health level

Cost Analysis of MRI Services in Iran: An Application of Activity Based Costing Technique.

Background:Considerable development of MRI technology in diagnostic imaging, high cost of MRI technology and controversial issues concerning official charges (tariffs) have been the main motivations to define and implement this study.Objectives:The present study aimed to calculate the unit-cost of MRI services using activity-based costing (ABC) as a modern cost accounting system and to fairly compare calculated unit-costs with official charges (tariffs).Materials and Methods:We included both direct and indirect costs of MRI services delivered in fiscal year 2011 in Shiraz Shahid Faghihi hospital. Direct allocation method was used for distribution of overhead costs. We used micro-costing approach to calculate unit-cost of all different MRI services. Clinical cost data were retrieved from the hospital registering system. Straight-line method was used for depreciation cost estimation. To cope with uncertainty and to increase the robustness of study results, unit costs of 33 MRI services was calculated in terms of two scenarios.Results:Total annual cost of MRI activity center (AC) was calculated at USD 400,746 and USD 532,104 based on first and second scenarios, respectively. Ten percent of the total cost was allocated from supportive departments. The annual variable costs of MRI center were calculated at USD 295,904. Capital costs measured at USD 104,842 and USD 236, 200 resulted from the first and second scenario, respectively. Existing tariffs for more than half of MRI services were above the calculated costs.Conclusion:As a public hospital, there are considerable limitations in both financial and administrative databases of Shahid Faghihi hospital. Labor cost has the greatest share of total annual cost of Shahid Faghihi hospital. The gap between unit costs and tariffs implies that the claim for extra budget from health providers may not be relevant for all services delivered by the studied MRI center. With some adjustments, ABC could be implemented in MRI centers. With the settlement of a reliable cost accounting system such as ABC technique, hospitals would be able to generate robust evidences for financial management of their overhead, intermediate and final ACs.

Reconfigurable Direct Allocation for Multiple Actuator Failures

Flight control systems are often equipped with reconfigurable control allocation schemes to redistribute control commands in the event of actuator failures. In this brief, a reconfiguration scheme is proposed and is based on the direct allocation method. An iterative algorithm is developed and uses the same lookup tables prepared offline for normal operations, thereby saving a considerable amount of computation time and process memory. To elucidate the effectiveness of the method, the proposed allocation algorithm is applied to a satellite launch vehicle model. Simulation results show satisfactory performance of the method in the presence of multiple actuator failures.

The Research on Ship Positioning’ Thruster Allocation Based on Evolutionary Algorithm

Ship Positioning’s Thruster Allocation is a nonlinear programming problem with nonlinear equality and inequality. Morgan's direct thruster allocation method is simple and allocation's speed is quick. And Sequential Quadratic Programming, evolutionary algorithm is used to solve more complex performance index and constrains, however, load balance is not considered. In this paper, performance index is improved considering load balance. And evolutionary algorithm is used to solve the problem. Results show that search time is long. In the future, heuristic based on solved problem operator should be used to decrease time of evolutionary algorithm. For example, setting forbidden operator to eliminate unfeasible solutions. Sequential Quadratic Programming could be used to solve the problem presented in this paper with improved performance index.

A Modified Direct Allocation Algorithm with Application to Redundant Actuators

Control allocation considers the problem of controlling instruction distribution for control systems with multiple and redundant actuators. This paper focuses on the direct allocation method, making the time requirement of the algorithm analogous compared with modified pseudoinverse redistribution methods, linear programming methods solved by simplex method, and sub-gradient optimization method. To reduce off-line computations of constructing the attainable moment set of actuators, a new approach based on the null space of the control effectiveness matrix is proposed, which is superior when the number of actuators is less than 10 compared with traditional method. To decrease on-line computations, an improvement method of searching the facet that is aligned with the desired moment is presented, shortening the search time by checking only the facets that lie around the desired moment. To find such facets, the vertices of the attainable moment set are normalized and saved during off-line computations. Simulation results show that at least 32.22% of off-line computation time would be saved using null space-based construction when the number of actuators is less than 10. In on-line computations, the modified method performs superiorly compared with the three aforementioned methods. Furthermore, it may solve the problem of control allocation efficiently when a remarkable large number of redundant actuators are configured.

Evaluation of Optimization Methods for Control Allocation

The performanceand computational requirements ofoptimization methodsfor control allocation areevaluated. Two control allocation problems are formulated: a direct allocation method that preserves the directionality of the moment and a mixed optimization method that minimizes the error between the desired and the achieved momentsaswellasthecontroleffort.Theconstrainedoptimizationproblemsaretransformedinto linearprograms so that they can be solved using well-tried linear programming techniques such as the simplex algorithm. A variety of techniques that can be applied for the solution of the control allocation problem in order to accelerate computations are discussed. Performance and computational requirements are evaluated using aircraft models with different numbers of actuators and with different properties. In addition to the two optimization methods, three algorithms with low computational requirements are also implemented for comparison: a redistributed pseudoinverse technique, a quadratic programming algorithm, and a e xed-point method. The major conclusion is that constrained optimization can be performed with computational requirements that fall within an order of magnitude of those of simpler methods. The performance gains of optimization methods, measured in terms of the error between the desired and achieved moments, are found to be small on the average but sometimes signie cant.Avariety ofissuesthataffecttheimplementation ofthevariousalgorithmsin ae ight-controlsystem are discussed.

Fast Implementation of Direct Allocation with Extension to Coplanar Controls

The direct allocation method is considered for the control allocation problem. The original method assumed that every three columns of the controls effectiveness matrix were linearly independent. Here, the condition is relaxed, so that systems with coplanar controls can be considered. For fast online execution, an approach using spherical coordinates is also presented, and results of the implementation demonstrate improved performance over a sequential search. Linearized state-space models of a C-17 aircraft and of a tailless aircraft are used in the evaluation. Oincreasethe reliability ofaircraft,cone gurations with a large numberofactuatorsandcontrolsurfacesareadvantageous.Recone gurable control laws may be used to exploit all of the available control power despite failures and damages. 1;2 Control allocation is the problem of distributing the control requirements among multiple actuators to satisfy the desired objectives while accounting for the limited range of the actuators. Although solutions exist for the control allocation problem, an issue of current interest is that of the feasibilityoftheirimplementationonexistingcomputersforaircraft with a large number of actuators. 3 The direct allocation approach 4i6 is based on the concept of the attainable moment set (AMS), which is the set of all of the moment vectors that are achievable within the control constraints. The methodofdirectallocation allowsoneto achieve100%oftheAMS, whereas some other approaches such as daisy chaining, pseudoinverse,and generalized inversesolutionshavebeen shown to achieve