Electrochemical and microfabrication strategies for remotely operated heavy metal sensor networks for water analysis : the dual challenges of calibration-less measurement and sample pretreatment.

Current heavy metal monitoring in water utilizes sophisticated instrumental methods at centralized laboratories. For many applications, a preferable approach is the deployment of remote sensor networks. To this end, electrochemical methods in conjunction with microfabricated sensors potentially offer the required sensitivity and practical advantages including inexpensive sensors, reduced need for manual operation, reduced energy requirements, and also takes advantage of existing technologies such as communications networks for real-time data acquisition. The remote sensor platform developed herein consists of a photo-lithographically patterned gold electrode on SiO2 substrate within a custom stopped-flow thin-layer cell (TLC). Metal concentrations were evaluated by anodic stripping coulometry (ASC), where it was possible to pre-concentrate all dissolved metals from the finite TLC volume in about a minute. Unlike previously reported ASC approaches which rely on either linear sweep voltammetry or chronopotentiometry, the ASC variant described herein utilizes a potential step to simultaneously strip all deposited metals. The use of a double potential step ASC method also allowed in situ blank subtraction without the need for a separate blank solution. To achieve selectivity, several deposition potentials are used to pre-concentrate only those metals which can be reduced at a given potential. This method is demonstrated to be capable of measuring 500 ppb As(III) to better than 10% error even in the presence of high interferent levels (1.3 ppm Cu2+, 500 ppb Cd2+, 500 ppb Pb2+, and 5 ppm Zn2+). Similar performance was possible for As(III) spiked Ohio River water after pH adjustment. For more negatively reduced metals, dissolved oxygen (DO) reduction interferes with stripping analysis. An indirect in-line electrochemical DO removal device (EDOR), utilizing a silver cathode to reduce DO in a fluidically isolated chamber from the sample stream, was therefore developed. This device is capable of 98 % DO removal at flow rates approaching 50 µL/min with power consumption as low as 165 mW hr L-1. Besides our specific stripping application, this device is well suited for Lab on Chip (LOC) applications where miniaturized DO removal and/or regulation are desirable

Power losses reduction of power transmission network using optimal location of low-level generation

Due to the growth of demand for electric power, electric power loss reduction takes great attention for the power utility. In this paper, a low-level generation or Distributed Generation (DG) has been used for transmission power losses reduction. Karbala city transmission network (which is the case study) has been represented by using MATLAB m-file to study the load flow and the power loss for it. The paper proposed the Particle Swarm Optimization (PSO) technique in order to find the optimal number and allocation of DG with the objective to decrease power losses as possible. The results show the effect of the optimal allocation of DG on power loss reduction

An optimal allocation of UPFC and transient stability improvement of an electrical power system: IEEE-30 buses

Recently, the expansion process of electrical networks has become crucial with the development of electrical systems. One of the active solutions to progress the performance of an electrical system is the usage of flexible AC transmission system (FACTS). As a new generation of telecommunications and power electronics technology, FACTS has provided a new viewpoint to increase the bearing capacity, better control the grid, and reduce costs. The unified power flow controller had a multi-purpose unit that could command the scenario of providing or consuming the power components and maintaining the bus voltage. The study's novelty resided in presenting a modified particle swarm optimization algorithm-based software system and applied a Newton-Raphson load flow solution to get the best solutions for optimal allocation of unified power flow controllers (UPFC). This study has focused on the functions of the UPFC electrical system with corresponding effects on transient stability. MATLAB software (Simulink/code) and excel sheet were performed on IEEE 30 buses as a case study. It has been shown the effectiveness of UPFC with fast response and autonomous command on the flow of power components. The dynamic response for stability improvement for some network buses had been verified to ensure the robustness of UPFC during a sudden disturbance in electrical load. The case study results illustrate that the number of UPFC increased with load increased by (14% and 21%)

Investigation of sub-module fault types of modular multi-level converters in HVDC networks

The modular multilevel converters (MMC) form the backbone of the modern voltage source converter (VSC) based HVDC system due to their unique features. Faults within the MMC affect the performance of the HVDC system. In this paper the fault types that can occur in the MMC are investigated. The reported work focuses on sub-module faults. A nine level MMC was simulated using PSCAD/EMTDC in this investigation

Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

AbstractThe interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT) capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS), utilizing the bridge-type Fault Current Limiter (FCL) with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS

A Computerized Tomographic Data Analysis System to Evaluate the Dental Implant Surface Roughness

AbstractDental implants have been progressively used in the recent years to support and retain dental prosthesis. Implant surface roughness has been suggested as a crucial factor in implant osseointegration and long term survival of the implant and prosthesis, where a key factor for the success or failure of dental implants is the manner in which stresses are transferred to surrounding bone. In this study completely edentulous patients were rehabilitated by implant retained over denture in which two implant systems with different surface roughness were used. Peri implant bone density in Hounsfield Units (HU) was evaluated by analyze Computerized Tomographic (CT) images to judge the behavior of an implant system under functional loading, where DICOM raw data was imported into the analysis proposed system to correlate the bone density regarding to the HU values. Results are compared with clinical readings and previous findings, which it showed that there is a difference in peri implant bone density around regularly patterned and randomly patterned implant surfaces

Polyunsaturated fatty acids influence offspring sex ratio in cows

Dietary polyunsaturated fatty acids (PUFAs) can influence fertility in farm animals. Some evidence in mice and sheep have suggested that PUFAs may influence offspring sex ratio, which may have significant value for cattle production. To test this hypothesis, three groups of Holstein cows were supplemented with either 0%, 3% or 5% protected fat (PF) in the form of calcium salt of fatty acids (rich in omega-6) from 14–21 days pre-partum until conception. Proven-fertile frozen semen from the same ejaculate was used for insemination. Calf sex recorded at birth was 8/19 (42.1%) male offspring in the control group, increasing to 14/20 (70%, P > 0.05) and 17/20 (85%, P < 0.05) in 3% and 5% PF, respectively. To test if this effect was caused by a direct influence on the oocyte, we supplemented bovine cumulus oocyte complexes during in vitro maturation with either omega-3 alpha-linolenic acid (ALA), omega-6 linoleic acid (LA) or trans-10, cis-12 conjugated linoleic acid (CLA). Sex ratio of the produced transferable embryos was determined using PCR of SRY gene. Similar to the in vivo results, sex ratio was skewed to the male side in the embryos derived from LA- and CLA-treated oocytes (79% and 71%) compared to control and ALA-treated oocytes (44% and 54%, respectively). These results indicate that both dietary and in vitro supplementation of omega-6 PUFAs can skew the sex ratio towards the male side in cattle. Further experiments are required to confirm this effect on a larger scale and to study the mechanisms of action that might be involved

Attitudes of Teachers of to the Upper Basic Stage Towards the use of E-learning Platforms in the Kasbah of Irbid District

&nbsp;&nbsp; هدفت الدراسة إلى الكشف عن اتجاهات معلمي المرحلة الأساسية العليا نحو استخدام منصات التعليم الإلكتروني في لواء قصبة إربد تبعاً لمتغيرات الجنس والمؤهل العلمي وسنوات الخبرة، ولتحقيق أهداف الدراسة استخدم المنهج الوصفي، وتم استخدام استبانة تألفت من (25) فقرة، بعد التأكد من صدقها وثباتها، تكونت عينة الدراسة من (306) من معلمي المرحلة الأساسية العليا في لواء قصبة إربد (136) معلماً، و(170) معلمة، أظهرت النتائج أن اتجاهات معلمي المرحلة الأساسية العليا نحو استخدام منصات التعليم الإلكتروني في لواء قصبة إربد جاءت متوسطة، كما أظهرت عدم وجود فروق ذات دلالة إحصائية لاستجابات أفراد عينة الدراسة حول اتجاهات معلمي المرحلة الأساسية العليا نحو استخدام منصات التعليم الإلكتروني تعزى لمتغيرات الجنس والمؤهل العلمي وسنوات الخبرة، وأوصت الدراسة بضرورة تنمية الاتجاهات الايجابية لدى المعلمين نحو استخدام منصات التعليم الإلكتروني وتفعيل المنصات التعليمية الإلكترونية في المدارس لما لها من أثر ايجابي على العملية التعليمية.The study aimed to reveal the attitudes of higher basic stage teachers towards the use of e-learning platforms in the Qasaba Irbid District, according to the variables of gender, educational qualification, and years of experience. The sample of the study consisted of (306) teachers of the upper basic stage in the Qasaba Irbid District (136) males, and (170) females. There are statistically significant differences in the responses of the study sample individuals about the attitudes of higher basic stage teachers towards the use of e-learning platforms due to the variables of gender, educational qualification and years of experience. Positive impact on the educational process