Undesirable Outputs’ Presence in Centralized Resource Allocation Model

Data envelopment analysis (DEA) is a common nonparametric technique to measure the relative efficiency scores of the individual homogenous decision making units (DMUs). One aspect of the DEA literature has recently been introduced as a centralized resource allocation (CRA) which aims at optimizing the combined resource consumption by all DMUs in an organization rather than considering the consumption individually through DMUs. Conventional DEA models and CRA model have been basically formulated on desirable inputs and outputs. The objective of this paper is to present new CRA models to assess the overall efficiency of a system consisting of DMUs by using directional distance function when DMUs produce desirable and undesirable outputs. This paper initially reviewed a couple of DEA approaches for measuring the efficiency scores of DMUs when some outputs are undesirable. Then, based upon these theoretical foundations, we develop the CRA model when undesirable outputs are considered in the evaluation. Finally, we apply a short numerical illustration to show how our proposed model can be applied

Beyond Codebook-Based Analog Beamforming at mmWave: Compressed Sensing and Machine Learning Methods

Analog beamforming is the predominant approach for millimeter wave (mmWave) communication given its favorable characteristics for limited-resource devices. In this work, we aim at reducing the spectral efficiency gap between analog and digital beamforming methods. We propose a method for refined beam selection based on the estimated raw channel. The channel estimation, an underdetermined problem, is solved using compressed sensing (CS) methods leveraging angular domain sparsity of the channel. To reduce the complexity of CS methods, we propose dictionary learning iterative soft-thresholding algorithm, which jointly learns the sparsifying dictionary and signal reconstruction. We evaluate the proposed method on a realistic mmWave setup and show considerable performance improvement with respect to code-book based analog beamforming approaches

Experimental and empirical model analysis of microsurface texturing on 316 L press-fit joints fabricated by selective laser melting

In this study, selective laser melting (SLM) was investigated for the manufacturing of 316L stainless steel press-fit joints. The accuracy of selective laser melting technique in fabrication of texture profile in shape, pitch and height of microsurface texturing was examined. The resulting insertion and removal forces achieved from the produced textured pins for cold-formed high-end fixation applications were studied. The experimental results showed that the shape, pitch and height of the texture, as well as the resultant bonding strength of the joints, can be effectively set via control of the SLM processing parameters. While trapezoidal and triangular shapes of the texture lead to stronger bonding compared with oval-shaped texture profiles, the texture height was found to have a predominant effect on bond strength. To a much lower extent, larger pitch distances also resulted in higher bond strengths. A combination of abrasive and adhesive wear mechanisms was detected via examination of the inner surface of the hub into which the press fit was inserted. Along with a process map of design of the microsurface texture geometry of metal interference fit joints, this paper also presents the underlying mechanics for their bonding. The SLM process is shown to present a useful one-step method for the manufacturing of knurl metallic interference fit pins of customisable and definable texture and ensuing bond strength

Лінійні коливання консольних циліндричних оболонок без неоднорідностей

Cylindrical shells are commonly used as elements of rockets, aircrafts and others structures. The natural frequencies and eigenmodes of the linear cantilever cylindrical shells are very important to predict the dynamic behavior of complex engineering structures. The Rayleigh-Ritz method is applied to analyze the eigenfrequencies and the eigenmodes of the cantilever cylindrical shells. The Donnell’s and Sanders-Koiter shell theories with orthogonal polynomials are used to study the shell linear vibrations. The eigenfrequencies and the eigenmodes of the cantilever shell are investigated. The eigenfrequencies, which are obtained by these two theories, are close. The obtained results are compared with the data, obtained by software ANSYS. The properties of the conjugate eigenmodes are analyzed. The results of the analysis are compared with the data of finite element calculations.Для розрахунку власних частот і форм коливань консольних циліндрових оболонок застосовується метод Релея-Ритца. Застосовуються теорії Сандерса-Коїтера і Доннела. Коливання конструкції розкладаються по ортогональних поліномах. Досліджуються властивості зв'язаних мод коливань. Результати аналізу порівнюються зі скінченно-елементними розрахунками

Effectiveness of intervention due to feedback on errors arising from inappropriate transportation and storage of blood bags in hospitals: a quasi-experimental study

Background: The limited supply of red blood cells (RBCs) for transfusion has clinical implications, and can lead to the introduction of different approaches in decreasing blood wastage and the safe and effective delivery of blood products. Objective: To identify the influences of feedback-based intervention on inappropriate temperatures during transportation and storage of blood bags. Methods: This was a quasi-experimental pretest-posttest design with a non-equivalent control group that was carried out on 200 RBC. The study was conducted in a teaching hospital in Mashhad, Iran, and in two periods during the same season: winter of 2015 (pre-intervention period) and winter of 2016 (post-intervention period). Staff of the blood bank department, as the intervention group, received the intervention including feedback regarding the inappropriate temperature in the blood bank during the pre-intervention period. The control group included personnel and nurses from the OR, CSICU, and transportation department, who did not receive any feedback. The effect of the intervention on the RBCs' temperature was evaluated by comparing the percentage of inappropriate temperature of RBC bags before and after the implementation of the intervention. Results: Inappropriate temperature in the blood bank decreased from 30% to 12% after the intervention was implemented (relative reduction of 60%). Meanwhile, there was even an increase in inappropriate temperature in the control group including OR (from 6.5% to 20.5%), CSICU (from 1% to 2.5%) and transportation (from 0.6% to 16.6%). Conclusion: The implementation of a feedback-based intervention to increase the awareness of the staff of critical conditions can improve conditions of blood storage and transport. The use of various interventions along with this type of intervention seems necessary to increase effectiveness. Funding: This research was part of the first author's MSc thesis which was supported by a grant from Mashhad University of Medical Science Research Council (Ref. no.: 950116; Date: September 7, 2016)