Experimental Verification of the Averaged Strain Energy Density Criterion for Brittle Fracture in Blunt V-Notches under Pure Compression

Strength of Materials - The goal of the present study is to verify experimentally the Averaged Strain Energy Density (ASED) criterion for brittle fracture in blunt V-notches under pure compression....     

Analysis of Effective Environmental Flow Release Strategies for Lake Urmia Restoration

Saline lakes have diminished considerably due to large-scale irrigation projects throughout the world. Environmental flow (EF) release from upstream reservoirs could help conserve and restore these lakes. However, experiences from regions lacking environmental legislation or with insufficient water resources management show that, despite EF allocation, farmers tend to use all available water for agriculture. In this study, we employed a new method for designing environmental flow release strategies to restore desiccated terminal lakes in arid and semi-arid regions with intensive cultivation within the catchment. The novelty of the method is that it takes into account farmers’ water use behavior and the natural flow regime in upstream systems to design an optimum monthly EF release strategy for reservoirs. We applied the method to the water resource system of Lake Urmia, once the largest saline lake in the Middle East and now one of the most endangered saline lakes in the world. The analysis showed that the EF released is exploited by lowland farmers before reaching Lake Urmia and that inflow to the lake from some rivers has decreased by up to 80%. We propose a new EF release strategy that requires a considerable change in practice whereby water is released in the shortest possible time (according to reservoir outlet capacity) during the period of lowest irrigation demand in winter. Restoring the lake to minimum ecological level would require 2.4–3.4 km³ EF allocation by different methods of release based on the recent condition (2002–2011) of the lake.     

Experimental and FEM failure analysis and optimization of a centrifugal-pump volute casing

Material and geometry are two key factors in ideal mechanical performance of centrifugal-pump casings engaged in high pressures.This paper presents the model generation, static structural analysis, and geometrical modifications performed for a failed volute casing of a real centrifugal-pump. Failure would be examined under hydrostatic test conditions. Finite Element Method is employed in stage of theoretical problem investigation.To control failure phenomenon, necessary geometrical modifications are applied to the model. Geometrical modifications must have the least effect on hydraulic performance and avoid excessive manufacturing costs.Finally, some test volute casings with new geometry would be built to experimentally validate the analytical results and inspect the hydraulic performance.     

新型电子器件和光学器件的共振隧穿结构

描述了一种新型共振隧穿结构器件，这种器件包含了通过可变间隙超晶格能量滤波器（ＶＳＳＥＦ）中的耦合量子附态的隧穿过程．论证了通过ＡｌＡｓ／ＧａＡｓＶＳＳＥＦ器件高能态和ＡｌＧａＡｓ／ＧａＡｓ超晶格受激态的共振隧穿，描述了这种器件作为较高功率微波源和共振隧穿晶体管的应用，并讨论了共振隧穿结构作为雪崩探测器和红外发射器等光学器件的潜在应用．     

Pharmacists'' concerns and suggestions related to the sale of tobacco and alcohol in pharmacies

A random sample of Pharmacists in Indiana was selected and surveyed regarding their thoughts and comments on the sale of tobacco and alcoholic products by pharmacies. A total of 212 pharmacists provided written responses to an open-ended question. The replies were then synthesized into major themes. The majority of comments categorized revealed strong opposition to pharmacies selling tobacco and alcohol products. The most frequently occurring message regarding the sale of these products by pharmacies was that it goes against the pharmacist's role as a professional health care provider and may harm their image. For some pharmacists, this issue posed a moral dilemma between caring for patient safety and the economic incentives provided by the sale of tobacco and alcohol. Based on these findings, a follow-up phone survey was conducted to solicit suggestions from pharmacists on how to advocate against the sale of tobacco and alcohol by pharmacies. The majority of pharmacists strongly recommended that they need to do more among themselves and within their store environment, rather than have regulations imposed on pharmacies when it comes to limiting the sale of these products.     

Experimental verification of RV-MTS model for fracture in soda-lime glass weakened by a V-notch

Fracture phenomenon was experimentally investigated in a soda-lime glass weakened by a V-notch under tensile-shear loading. Fracture tests were conducted using a new test sample called the V-notched Brazilian disc (V-BD) specimen. The fracture resistance and fracture initiation angle were obtained initially from the test results. Afterward, a fracture model was utilized to estimate the experimental results. Very good correlation was found between the experimental and theoretical results both for the fracture resistance and the fracture initiation angle in notches having different notch angles and various notch tip radii. Experimental results revealed that for a constant notch tip radius, the failure load under pure tensile loading conditions decreases as the notch angle increases. For a constant notch angle, as the notch tip radius increases, the fracture load in the soda-lime glass V-BD specimens enhances in the whole domain from pure tensile to pure shear loading. Moreover, for a constant notch tip radius, the notch angle has almost no effect on the fracture initiation angle when the specimen is predominantly under tensile loading conditions.     

Variable‐rate adaptive modulation with optimum switching thresholds for cooperative systems with relay selection

In this paper, the performance of variable‐rate adaptive modulation schemes in the amplify‐and‐forward cooperative systems with relay selection is analyzed over Rayleigh fading channels. We consider constant power and discrete‐rate adaptive multi‐level modulation techniques. The switching levels required for discrete‐rate adaptive modulation have been determined for two schemes, namely fixed switching levels and optimum switching levels, both respecting a target bit error rate requirements, where in the later scheme, the switching levels are optimally determined in a way that the average spectral efficiency of the system is maximized. Two M‐ary modulation schemes, namely quadrature amplitude modulation and phase shift keying, are considered. Closed‐form expressions are derived for three performance metrics, namely average spectral efficiency, outage probability, and average bit error rate, for two cases: independent and identically distributed fading relay links and independent and non‐identically distributed links. It is shown that, compared with using fixed switching levels, employing optimum switching levels provides a slight improvement in the spectral efficiency and moderate improvements in the signal‐to‐noise ratio gain and in the outage probability of the system. It is also shown that compared with the independent and identically distributed links, independent and non‐identically distributed relay links yield a slight increase in the signal‐to‐noise ratio gain and a slight decrease in the diversity order of the system. Copyright © 2011 John Wiley & Sons, Ltd.     

Application of ANFIS to predict crop yield based on different energy inputs

In this paper, adaptive neuro-fuzzy inference system (ANFIS) was used to predict the grain yield of irrigated wheat in Abyek town of Ghazvin province, Iran. Due to large number of inputs (eight inputs) for ANFIS, the input vector was clustered into two groups and two networks were trained. Inputs for ANFIS 1 were diesel fuel, fertilizer and electricity energies and for ANFIS 2 were human labor, machinery, chemicals, water for irrigation and seed energies. The RMSE and R² values were found 0.013 and 0.996 for ANFIS 1 and 0.018 and 0.992 for ANFIS 2, respectively. These results showed that ANFIS 1 and ANFIS 2 could well predict the yield. Finally, the predicted values of the two networks were used as inputs to the third ANFIS. The results indicated that the energy inputs in ANFIS 1 have a greater impact on the final yield production than other energy inputs. Also, the RMSE and R² values for ANFIS 3 were 0.013 and 0.996, respectively. These results showed that ANFIS 1 and the combined network (ANFIS 3) could both predict the grain yield with good accuracy.     

The Influence of Cathode Voltage and Discharge Current on Neutron Production Rate of Inertial Electrostatic Confinement Fusion (IR-IECF)

In this research effect of gas pressure, discharge current and cathode voltage on the neutron production rate in IR-IECF device is studied. In the experiment discharge current from 20 to 100 mA was tunable by deuterium gas pressure from 6.4 × 10^?3 mbar to 1.7 × 10^?2 mbar and cathode voltage was changed from 20 to 80 kV. Moreover, maximum value of neutron production rate can be achieved in optimum pressure and discharge current at a constant voltage.     

Preliminary Results of the 115 kJ Dense Plasma Focus Device IR-MPF-100

This work summarizes the design and construction of the first Iranian 115 kJ Mather type plasma focus (PF) machine (IR-MPF-100). This machine consists of a 6.25 cm radius and 22 cm height brass made anode with a 50 mm height insulator which separates the anode and cathode electrodes. Twelve copper made 22 cm height rods play the role of cathode with 10.2 cm radius. Twenty four 6 μF capacitors were used with the maximum charging voltage of 40 kV (maximum energy of 115 kJ) as the capacitor bank and maximum theoretical current around 1.224 MA. The total inductance of the system is 120 nH. By using NE-102 plastic Scintillator, Rogowski coil, current and voltage probes, hard X-ray, current derivative, current and voltage signals of IR-MPF-100 were measured. The primary result of neutron detection by neutron activation counter represents approximately 10⁹ neutrons per shot at 65 kJ discharge energy while using deuterium filling gas. Also IR-MPF-100 PF has been tested successfully at 90 kJ by using the argon gas.