Techno-economical evaluation of electrocoagulation for the textile wastewater using different electrode connections

The bench scale of an electrocoagulation (EC) unit requires a detailed study discerning the effects of continuous variables such as pH, current density and operating time, and type variables such as electrode material and connection mode. This paper presents the results of the treatment of a textile wastewater by EC process. Two electrode materials, aluminum and iron, were connected in three modes namely, monopolar-parallel (MP-P), monopolar-serial (MP-S), and bipolar-serial (BP-S). COD and turbidity removals were selected as performance criteria. For a high COD removal, acidic medium is preferable for both electrode materials. For a high turbidity removal, acidic medium is preferable for aluminum, and neutral medium for iron. High current density is favorable for both removals in the case of iron. In the aluminum case, the current density exhibits a pronounced effect on COD removal, depending strongly on the connection mode, but it has a negligible effect on the turbidity removal. MP-P with iron or MP-S with aluminum electrode are suitable configurations in regard with the overall process performance. Moreover, process economy is as important as removal efficiencies during the process evaluation task. Various direct and indirect cost items including electrical, sacrificial electrodes, labor, sludge handling, maintenance and depreciation costs have been considered in the calculation of the total cost. The results show that MP-P mode is the most cost-effective for both electrode types. Both electrodes show similar results in reducing COD and turbidity, but iron is preferred as a low cost material. Finally, a comparative study showed that EC was faster and more economic; consumed less material and produced less sludge, and pH of the medium was more stabilized than chemical coagulation (CC) for similar COD and turbidity removal levels. For CC, FeCl(3) was the preferable salt in view of its techno-economic performance. On the other hand, iron was the preferred electrode material in EC with MP-P system in experimental conditions such as, 30 Am(-2) of current density and 15 min of time, the treatment cost was $ 0.245 m(-3). Consequently, the operating cost of CC was 3.2 times as high as the operating cost of EC.     

The relationship between glutathione peroxidase and bioimpedance parameters in nondiabetic hemodialysis patients

There is growing evidence from experimental and clinical studies that oxidative stress is involved in the pathogenesis of malnutrition. This cross‐sectional study aimed to investigate the relationship between glutathione peroxidase (GPx) levels as a marker of antioxidant status and the nutritional status assessed by bioimpedance analysis (BIA). Ninety‐seven nondiabetic stable outpatient uremic adults undergoing chronic hemodialysis (HD) were recruited for this study. Impedance measurements were performed using a multifrequency bioelectrical impedance analyzer after dialysis. GPx levels correlated with intracellular water (ICW) (r = 0.341, P = 0.011), ICW/total body weight (r = 0.320, P = 0.017), lean body mass (r = 0.300, P = 0.026) and total body cell mass (r = 0.339, P = 0.011). When patients were divided into two groups according to mean GPx levels (83.9 U/gr hemoglobin), the patients with higher GPx (GPx > 83.9 U/gr hemoglobin) had higher albumin (P = 0.038), lean body mass (P = 0.026), ICW (P = 0.011), and total body cell mass (P = 0.011) compared with those with lower GPx (GPx ≤ 83.9 U/gr hemoglobin). Furthermore, in the patients with higher GPx, body fat; extracellular water/total body water; illness marker and body fat mass index were lower than other group. In conclusion, our results reveal correlation indicating a relationship between antioxidant status (as measured by GPx) and nutritional status as assessed by BIA in nondiabetic HD patients.     

Critical and emerging technologies in Materials,Manufacturing, and Industrial Engineering: A study for priority setting

Technologies that were assumed to be critical or emerging in Materials, Manufacturing, and Industrial Engineering were combined from different sources. These were compared to recent data and trends based on publications as well as patents in these fields. Some of these technologies were found to be non-critical or non-emergent. Top-ten lists of critical and emerging technologies were derived using simple statistical tools and easily accessible databases. The present methodology is proposed as an effective procedure for priority setting in science and technology policy making. This revised version was published online in June 2006 with corrections to the Cover Date.     

A framework for capturing and analyzing the failures due to system/component interactions

To keep up with the speed of globalization and growing customer demands for more technology‐oriented products, modern systems are becoming increasingly more complex. This complexity gives rise to unpredictable failure patterns. While there are a number of well‐established failure analysis (physics‐of‐failure) models for individual components, these models do not hold good for complex systems as their failure behaviors may be totally different. Failure analysis of individual components does consider the environmental interactions but is unable to capture the system interaction effects on failure behavior. These models are based on the assumption of independent failure mechanisms. Dependency relationships and interactions of components in a complex system might give rise to some new types of failures that are not considered during the individual failure analysis of that component. This paper presents a general framework for failure modes and effects analysis (FMEA) to capture and analyze component interaction failures. The advantage of the proposed methodology is that it identifies and analyzes the system failure modes due to the interaction between the components. An example is presented to demonstrate the application of the proposed framework for a specific product architecture (PA) that captures interaction failures between different modules. However, the proposed framework is generic and can also be used in other types of PA. Copyright © 2007 John Wiley & Sons, Ltd.     

Modal analysis of multi-cracked beams with circular cross section

This paper proposes a numerical model that combines the finite element and component mode synthesis methods for the modal analysis of beams with circular cross section and containing multiple non-propagating open cracks. The model virtually divides a beam into a number of parts from the crack sections and couples them by flexibility matrices considering the interaction forces that are derived from the fracture mechanics theory. The main feature of the presented approach is that the natural frequencies and mode shapes of a beam with an arbitrary number of cracks and any kind of two end conditions can be conveniently determined with a reasonable computational time. Three numerical examples are given to investigate the effects of location and depth of cracks on the natural frequencies and mode shapes of the beams. Moreover, it is shown through these examples that the evaluation of modal data obtained by the proposed model gives valuable information about the location and size of defects in the beams.     

URAP-TR: a national ranking for Turkish universities based on academic performance

This study describes the basic methodological approach and the results of URAP-TR, the first national ranking system for Turkish universities. URAP-TR is based on objective bibliometric data resources and includes both size-dependent and size-independent indicators that balance total academic performance with performance per capita measures. In the context of Turkish national university rankings, the paper discusses the implications of employing multiple size-independent and size-dependent indicators on national university rankings. Fine-grained ranking categories for Turkish universities are identified through an analysis of ranking results across multiple indicators.     

Think globally act locally approach for the synthesis of a liveness-enforcing supervisor of FMSs based on Petri nets

This paper, by using Petri nets (PNs), reports a general approach, called a think globally, act locally (TGAL) method, to compute liveness-enforcing supervisors (LES) for flexible manufacturing systems (FMSs) prone to deadlocks. A place called global sink/source place (GP) is introduced provisionally help us to decide a set of monitors such that deadlock states can be removed. The TGAL method proceeds with liveness enforcement by an iterative way in which a complete state enumeration is computed at each step. The resulting LES is generally maximally permissive or suboptimal, without solving intractable integer linear programming (ILP) problems. Given a system, a sufficient condition is developed to decide whether the TGAL method can find maximally permissive, that is, optimal supervisors. Several typical FMSs popularly studied in the literature are used as the examples to demonstrate the proposed method.     

Active carbon/graphene hydrogel nanocomposites as a symmetric device for supercapacitors

Activated carbons (ACs) are successfully synthesized from Elaeagnus grain by a simple chemical synthesis methodology and demonstrated as novel, suitable supercapacitor electrode materials for graphene hydrogel (GH)/AC nanocomposites. GH/AC nanocomposites are synthesized via hydrothermal process at temperature of 180°C. The low-temperature thermal exfoliation approach is convenient for mass production of graphene hydrogel (GH) at low cost and it can be used as electrode material for energy storage applications. The GH/AC nanocomposites exhibit better electrochemical performances than the pure GH. Electrochemical performance of the electrodes is studied by cyclic voltammetry, and galvanostatic charge-discharge measurements in 1.0 M H₂SO₄ solution. A remarkable specific capacitance of 602.36 Fg^?1 (based on GH/AC nanocomposites for 0.4 g AC) is obtained at a scan rate of 1 mVs^?1 in 1 M H₂SO₄ solution and 155.78 Fg^?1 for GH. The specific capacitance was increased 3.87 times for GH/AC compared to GH electrodes. Moreover, the GH/AC nanocomposites for 0.2 g AC present excellent long cycle life with 99.8% specific capacitance retained after 1000 charge/discharge processes. Herein, ACs prepared from Elaeagnus grain are synthesized GH and AC supercapacitor device for high-performance electrical energy storage devices as a promising substitute to conventional electrode materials for EDLCs.     

Magnetism and Half-Metallicity in the Fe<Subscript>2</Subscript>ZrP Heusler Alloy

The electronic structure and magnetic properties of the Fe₂ZrP full-Heusler compound has been investigated by using ab initio calculations with the full-potential linearized augmented plane wave (FLAPW) method. The exchange-correlation functionals are taken into account within the generalized gradient approximation (GGA). Energetically, the AlCu₂Mn-type structure of the full-Heusler Fe₂ZrP is energetically more preferable than that of the CuHg₂Ti-type structure and it exhibits half-metallic ferrimagnet. The calculated total spin moment is found as 1 μ _B at the equilibrium lattice constant a ₀=5.90Å which remarkably agrees with the Slater-Pauling rule of M _t = Z _t ?24. While the spin-up band is metallic, the spin-down band has a semiconductor behavior with a gap of 0.593 eV and the spin-flip gap is 0.129 eV. The negative formation energy is shown as an evidence of the thermodynamic stability of alloy. The dependencies of the magnetic and electronic properties on the lattice constant are also discussed. The estimated Curie temperature is 752 K in the mean field approximation.     

Behavior of RC T-section beams strengthened with CFRP strips,subjected to cyclic load

This paper presents results of an experimental investigation on T-section reinforced concrete (RC) beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) strips. Specimens, one of which was the control specimen and the remaining six were the shear deficient test specimens, were tested under cyclic load to investigate the effect of CFRP strips on behavior and strength. Five shear deficient specimens were strengthened with side bonded and U-jacketed CFRP strips, and remaining one tested with its virgin condition without strengthening. The type and arrangement of CFRP strips and the anchorage used to fasten the strips to the concrete are the variables of this experimental work. The main objective was to analyze the behavior and failure modes of T-section RC beams strengthened in shear with externally bonded CFRP strips. According to test results premature debonding was the dominant failure mode of externally strengthened RC beams so the effect of anchorage usage on behavior and strength was also investigated. To verify the reliability of shear design equations and guidelines, experimental results were compared with all common guidelines and published design equations. This comparison and validation of guidelines is one of the main objectives of this work. The test results confirmed that all CFRP arrangements differ from CFRP strip width and arrangement, improved the strength and behavior of the specimens in different level significantly.