Reliability of MSF processes based on operation history

Reliability of MSF processes are estimated using time-dependent fault tree analysis of major critical systems. Failure data are obtained from the operation records of Jeddah I since it is one of the oldest plants still in operation in a relatively harsh environment. Industrial failure data are also used to complement historic data. The analysis shows areas where design improvements can be made to enhance MSF processes availability.     

On the relative Coulombic effectiveness and profitability of electrolysis via intermittent current

The current and energy utilization of intermittent current electrolysis is analysed, and feasibility regions in terms of product costs and profitability are discussed using the deposition of copper as an illustrative example.Nomenclature A electrode area - b geometric aspect ratio,W/L - c ₀ bulk electrolyte concentration - C _E Unit price or electricity, including generation of intermittent potential-drop train (MU J^–1) - C _p unit price of electrolysis product (MU kg^–1) - D electrolyte diffusivity - E relative Coulombic effectiveness - F Faraday's constant - h chart recording heights (Fig. 1) - I current - I _m maximum allowable current in d.c. electrolysis - k mass transfer coefficient - L length of straight section in current response (Fig. 1) - MU arbitrary monetary unit - m _e electrochemical coefficient of product (kg C^–1) - n number of electrons involved in cathode reaction - N number of cycles in intermittent potential train - P unit profit (MU kg^–1) - r chart recording height ratio, or corresponding current ratioh ₁/h ₂=I ₁/I ₂ - S _I root mean square of deviations about the fitted curve - t time - V _c magnitude of intermittent potential drop (V) - V _m maximum allowable potential drop in d.c. electrolysis (V) - W length of trapezoidal portion in response (c) (Fig. 1) - X potential drop ratioV _c/V _m - Y ratio of unit profits - Z _i functions defined in Equation 9b (Z₁) and Equation 10b (Z₂) - lumped parameter (Equation 4) - chart response angle - half-period of intermittent potential-drop Train     

Laser beam machining of zirconia ceramic: An investigation of micro-machining geometry and surface roughness

Journal of Mechanical Science and Technology - Micro-machining of dental ceramics namely as zirconium oxide is carried out through laser beam machining. Micro-channels of different sizes are...     

Impact of bismuth oxide on the structure,optical features and ligand field parameters of borosilicate glasses doped with nickel oxide

Understanding the impact of bismuth cations on the optical properties of borosilicate glass is significant for manipulating borate glass applications. In this paper, the influence of bismuth cations on both structural and optical properties of borosilicate glass doped with NiO was investigated. Different glass samples, containing different amounts of Bi₂O₃ and a constant amount of NiO, were prepared and studied. Infrared (IR) analysis was carried out to study the internal structure within the investigated glass samples. Optical absorption studies were performed to investigate the impact of Bi₂O₃ content on optical properties of the BiBaNiB-glasses. Astonishingly, with Bi₂O₃ addition, an absorption band at 380 nm has appeared. Moreover, this band is overlapped with the Urbach edge; which regularly produced an artificial edge-like feature at ~450 nm. A detailed deconvolution protocol has been implemented for an appropriate understanding of these spectra and unraveling the hidden Urbach edge. Optical band gap energy, linear and nonlinear refractive index for each BiBaNiB sample were calculated. Furthermore, the metallization criterion was calculated to examine the metallic or insulating nature of the BiBaNiB-glasses. The values of the nonlinear third-order susceptibility and nonlinear refractive index were increased with Bi₂O₃ doping. The BiBaNiB-glasses exhibited outstanding stability and optical band gap than the pristine glass sample, which makes it possible for practical applications.     

Roles for endothelial zinc homeostasis in vascular physiology and coronary artery disease

Abstract

The discovery of the roles of nitric oxide (NO) in cardiovascular signaling has led to a revolution in the understanding of cardiovascular disease. A new perspective to this story involving zinc (Zn) is emerging. Zn and its associated Zn transporter proteins are important for the integrity and functions of both the large conduit vessels and the microvascular resistance vessels. The Zn and NO pathways are tightly coordinated. Zn ions are required for the dimerization of endothelial nitric oxide synthase and subsequent generation of NO while generation of NO leads to a rapid mobilization of endothelial Zn stores. Labile Zn may mediate important downstream actions of NO including vascular cytoprotection and vasodilation. Several vascular disease risk factors (including aging, smoking and diabetes) interfere with Zn homeostatic mechanisms and both hypozincaemia and Zn transporter protein abnormalities are linked to atherosclerosis and microvascular disease. Some vegetarian diets and long-term use of certain anti-hypertensives may also impact on Zn status. The available evidence supports the existence of a Zn regulatory pathway in the vascular wall that is coupled to the generation and actions of NO and which is compromised in Zn deficiency with consequent implications for the pathogenesis and therapy of vascular disease.     

Copper effects in mechanical,thermal and electrical properties of rapidly solidified eutectic Sn–Ag alloy

The Sn–3.5 wt%Ag alloy considered as a good alternative to Pb–Sn alloys. This study aims to investigate the effects of Cu or Sb additions by 3 or 5 wt% to melt-spun Sn–3.5%Ag alloy. Ternary melt-spun Sn–Ag–Cu and Sn–Ag–Sb alloys investigated using X-ray diffractions (XRD), Scanning electron microscope (SEM), Dynamic resonance technique (DRT), Instron machine, Vickers hardness tester and Differential scanning calorimetry (DSC). The results revealed that the microstructures of the β-Sn phase, Ag₃Sn and Cu₃Sn intermetallic compounds (IMCs) in the solder matrices were refined due to the effect of Cu additions and melt-spun process. Moreover, increasing Cu content promotes Ag₃Sn intermetallic compound (IMC) formation. Consequently, the addition of “3 wt%” of Cu reduced the creep rate ? from (3.79?×?10^?3) to (1.65?×?10^?3) and delayed the fracture point. The tensile results showed an improvement in Young’s modulus by 47% (30.3 GPa), ultimate tensile strength (UST) by 11.6% (23.9 MPa), and in toughness by 20.5% (952.32 J/m³) compared to the eutectic Sn–Ag alloy. Vickers hardness has improved by 3.3% (136.71 MPa) and thermal activation energy by 54% (90.40 KJ/mol) when compared with that of eutectic Sn–Ag alloy. Those improvements are related to the lack of lattice strain from 7.56?×?10^?4 without “3 wt%” of Cu to 5.26?×?10^?4 with “3 wt%” of Cu. Its melting temperature (T_m) increased by 3 °C due to Ag₃Sn IMC increased and Cu₃Sn formation, but the pasty rang (mushy zone) decreased by 4 °C with “3 wt%” of Cu. The small lattice strains resulted with “3 wt%” of Cu made the electrical resistivity of this alloy more stable at elevated temperatures. The mechanical, thermal and electrical improvements of Sn_93.5–Ag_3.5–Cu₃ alloy provide good physical performance for soldering process and electronic assembly.     

Performance of Gradient-Based Optimizer for Optimum Wind Cube Design

Renewable energy is a safe and limitless energy source that can be utilized for heating, cooling, and other purposes. Wind energy is one of the most important renewable energy sources. Power fluctuation of wind turbines occurs due to variation of wind velocity. A wind cube is used to decrease power fluctuation and increase the wind turbine’s power. The optimum design for a wind cube is the main contribution of this work. The decisive design parameters used to optimize the wind cube are its inner and outer radius, the roughness factor, and the height of the wind turbine hub. A Gradient-Based Optimizer (GBO) is used as a new metaheuristic algorithm in this problem. The objective function of this research includes two parts: the first part is to minimize the probability of generated energy loss, and the second is to minimize the cost of the wind turbine and wind cube. The Gradient-Based Optimizer (GBO) is applied to optimize the variables of two wind turbine types and the design of the wind cube. The metrological data of the Red Sea governorate of Egypt is used as a case study for this analysis. Based on the results, the optimum design of a wind cube is achieved, and an improvement in energy produced from the wind turbine with a wind cube will be compared with energy generated without a wind cube. The energy generated from a wind turbine with the optimized cube is more than 20 times that of a wind turbine without a wind cube for all cases studied.     

Design and Properties of New Lead-Free Solder Joints Using Sn-3.5Ag-Cu Solder

This article aims to reduce the melting temperature of lead-free solder alloy and promote its mechanical properties. Eutectic tin-silver lead-free solder has a high melting temperature 221 ^°C used for electronic component soldering. This melting temperature, higher than that of lead–tin conventional eutectic solder, is about 183 ^°C. The effect of the melt spinning process and copper additions into eutectic Sn-Ag solder enhances the crystallite size to about 47.92 nm which leads to a decrease in the melting point to about 214.70 ^°C, where the reflow process for low heat-resistant components on print circuit boards needs lower melting point solder. The results showed the presence of intermetallic compound Ag₃Sn formed in nano-scale at the Sn-3.5Ag alloy due to short time solidification. The presence of new intermetallic compound, IMC from Ag_0.8Sn_0.2 and Ag phase improves the mechanical properties, and then enhances the micro-creep resistance especially at Sn-3.5Ag-0.7Cu. The higher Young’s modulus of Sn-3.5Ag-0.5Cu alloy 55.356 GPa could be attributed to uniform distribution of eutectic phases. Disappearance of tin whiskers in most of the lead-free melt-spun alloys indicates reduction of the internal stresses. The stress exponent (n) values for all prepared alloys were from 4.6 to 5.9, this indicates to climb deformation mechanism. We recommend that the Sn_95.7-Ag_3.5-Cu_0.7 alloy has suitable mechanical properties, low internal friction 0.069, low pasty range 21.7 ^°C and low melting point 214.70 ^°C suitable for step soldering applications.     

Temperature and Spatiotemporal Variability of Salicylihalamide A in the Sponge <Emphasis Type="Italic">Haliclona</Emphasis> sp.

The production of salicylihalamide A by the marine sponge Haliclona sp. was investigated. Samples of the two morphologies (green and brown) were collected from four locations covering approximately 1,200 km of coastline. Temporal variation between winter and summer was also examined at Bremer Bay. Chemical profiling by using liquid chromatography coupled with ultra violet detection and mass spectrometry showed that salicylihalamide A was produced only by the green morphology. Salicylihalamide A concentration was significantly correlated to water temperature but not to the size or depth of the sponge. Salicylihalamide A concentration was found to differ significantly among locations (Bremer Bay 13.5 μg g⁻¹, Hamelin Bay 11 μg g⁻¹, Rottnest Island 9.9 μg g⁻¹, and Jurien Bay 8.5 μg g⁻¹) partially accounted for by the influence of water temperature. A difference between seasons was also observed in Bremer Bay (summer concentration of 13.5 μg g⁻¹ vs. winter concentration of 8.2 μg g⁻¹). Environmental and physiological factors appear to be important in the production of salicylihalamide A by the green morphology. Additionally, the brown morphology does not produce salicylihalamide A, thus adding to the evidence that this morphology may be a different species.