Pulsed CO2 laser-induced gas plasma spectroscopy based on single beam splitting for trace metal analysis on a material surface

Laser-induced gas plasma spectroscopy based on pulsed CO₂ laser beam splitting has been applied to the problem of trace film analysis on the silicon surface. In this study, 2.1?J of laser energy (70% of the laser beam) was focused at a 10-degree incidence on a metal mesh attached to a sample surface containing trace metal elements in order to produce a gas plasma. The remaining part of the laser beam (approximately 30% or 0.9?J) was employed to vaporize a film which had been deposited on the material by focusing the laser beam 3?cm under the surface. In this scheme, the vaporized metal film moves into the gas plasma region, in which the dissociation and excitation takes place. Our measurements show that the detection of Cr on the silicon surface can be made with high sensitivity. The limit of detection of Cr in the silicon material was approximately 7.5?×?10¹²?atom/cm².     

Genetic algorithm tuned PI controller on PMSM simplified vector control

A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced efficiently. Simplified vector control, which has simple control structure, is utilized as the permanent magnet synchronous motor control algorithm and genetic algorithm is used to tune three PI controllers used in simplified vector control. The control performance is obtained from simulation and investigated to verify the feasibility of the algorithm to be applied in the real application. Simulation results show that the speed and torque responses of the system in both continuous time and discrete time can achieve good performances. Furthermore, simplified vector control combined with genetic algorithm has a similar perfofmance with conventional field oriented control algorithm and possible to be realized into the real simple application in the future.     

Geranylgeraniol Inhibits Lipopolysaccharide-Induced Inflammation in Mouse-Derived MG6 Microglial Cells via NF-κB Signaling Modulation

Persistent inflammatory reactions in microglial cells are strongly associated with neurodegenerative pathogenesis. Additionally, geranylgeraniol (GGOH), a plant-derived isoprenoid, has been found to improve inflammatory conditions in several animal models. It has also been observed that its chemical structure is similar to that of the side chain of menaquinone-4, which is a vitamin K₂ sub-type that suppresses inflammation in mouse-derived microglial cells. In this study, we investigated whether GGOH has a similar anti-inflammatory effect in activated microglial cells. Particularly, mouse-derived MG6 cells pre-treated with GGOH were exposed to lipopolysaccharide (LPS). Thereafter, the mRNA levels of pro-inflammatory cytokines were determined via qRT-PCR, while protein expression levels, especially the expression of NF-κB signaling cascade-related proteins, were determined via Western blot analysis. The distribution of NF-κB p65 protein was also analyzed via fluorescence microscopy. Thus, it was observed that GGOH dose-dependently suppressed the LPS-induced increase in the mRNA levels of Il-1β, Tnf-α, Il-6, and Cox-2. Furthermore, GGOH inhibited the phosphorylation of TAK1, IKKα/β, and NF-κB p65 proteins as well as NF-κB nuclear translocation induced by LPS while maintaining IκBα expression. We showed that GGOH, similar to menaquinone-4, could alleviate LPS-induced microglial inflammation by targeting the NF-kB signaling pathway.     

Role of interfaces in damage process of irradiated lithium aluminate nanocrystals

Molecular dynamics simulations were performed to understand the differences in the response of single crystal and nanocrystalline γ-LiAlO₂ to energy deposition by 10 keV Li recoils. The simulations are performed at 573 K and focus on the damage production in the absence of thermal annealing. The grain boundaries in the nanocrystals are found to be amorphous. Analyses of the fate of the beam ions show that the amorphous grain boundaries and differently oriented nanograins increase the number of backscattered ions and decrease the number of transmitted ions. Damaged regions protruding from the grain boundaries provide a direct evidence of the role of the grain boundaries as scattering centers in collision cascades. The simulations show that the defect density produced in the nanocrystals is about twice that in the single crystals. In both samples, Li defects account for 70% of the defects, demonstrating that LiO₄ tetrahedra are much more susceptible to damage than AlO₄ tetrahedra. Furthermore, Li defects occur preferentially near grain boundaries. Diffusion simulations confirm the limited thermal diffusion of defects at 573 K, effectively separating the damage production from thermal annealing in the irradiation simulations. Nevertheless, the mean square displacements of grain-boundary defects are found to be larger than lattice defects and surface defects.     

Measurement of handle forces for crimping connectors and cutting cable in the electric power industry

Overhead and underground line work in the electric power industry is physically very strenuous and can expose workers to musculoskeletal disorders (MSDs), particularly in the upper extremity. Crimping compression connectors—such as sleeve connectors and lugs—and cutting cables are two of the most frequent tasks that line workers perform. Line workers at many utilities in the US crimp connectors and cut cable with long-handled manual tools. However, the actual magnitude of the forces applied to the handles of these tools is not known. The objectives of this laboratory study were to measure the forces applied to the handles of a manual press and a manual cutter in order to connect typical wire gauges and cut common cables, respectively. The handles of the manual press and cutter were attached to the drive cylinder and load cell of an Instrom Material Testing System, and peak forces exerted against the handles were measured. Results showed that the outer die of the manual press required about 50% more handle force than crimping connectors with the inner die location. The peak handle forces required to cut aluminum conductor cable as large as 2 cm diameter exceeded 500 N and were about 200 N greater than the peak forces to compress connectors manually. When the peak force data were compared to strength capabilities reported in the literature, less than 1% of the general population was found to have the maximum strength to manually make one crimp on a common overhead connector. Less than 1% and approximately 50% of the female and male general population, respectively, were found to have the maximum strength to manually cut a cable with a 2 cm diameter conductor. Handle force data from this study provide a biomechanical framework for explaining how the job demands of overhead and underground line workers could possibly cause MSDs.

Relevance to industry

Electric power utilities can review their work practices and tools in order to determine whether they can reduce the exposure of their workers to risk factors of MSDs, as well as reduce their cost of health care. Manufacturers of crimping and cutting tools can use the experimental approach in this study to measure the external forces required for their respective tools and then set quantitative force benchmarks to improve the design of their tools.     

Low energy ion‐solid interactions and chemistry effects in a series of pyrochlores

The effect of chemistry on low energy recoil events was investigated at 10 K for each type of atom in pyrochlores, using molecular dynamics simulation. Contour plots of the threshold displacement energy (E_d) in Gd₂Zr₂O₇ have been produced along more than 80 directions for each individual species. The E_d surface for each type of atom in Gd₂Zr₂O₇ is highly anisotropic; E_d of Zr exhibits the largest degree of anisotropy, while that of O_8b exhibits the smallest. The recommended values of E_d in Gd₂Zr₂O₇ based on the observed minima are 56, 94 and 25 eV, respectively, for Gd, Zr, and O. The influence of cation radius on E_d in pyrochlores A₂B₂O₇ (with A‐site ranging from Lu³⁺ to La³⁺ and B‐site ranging from Ti⁴⁺ to Ce⁴⁺) was also investigated along three directions [100], [110], and [111]. The E_d in pyrochlores strongly depended on the atom type, atom mass, knock‐on direction, and lattice position. The defects produced after low energy displacement events included cation antisite defects, cation Frenkel pairs, anion Frenkel pairs, various vacancies, and interstitials. Ce doping in pyrochlores may affect the radiation response, because it resulted in drastic changes in cation and anion displacement energies and formation of an unusual type of anti‐site defect. This work demonstrates links between E_d and amorphization resistance.     

Application of relevance vector machine and logistic regression for machine degradation assessment

Degradation parameter or deviation parameter from normal to failure condition of machine part or system is needed as an object of prediction in prognostics method. This study proposes the combination between relevance vector machine (RVM) and logistic regression (LR) in order to assess the failure degradation and prediction from incipient failure until final failure occurred. LR is used to estimate failure degradation of bearing based on run-to-failure datasets and the results are then regarded as target vectors of failure probability. RVM is selected as intelligent system then trained by using run-to-failure bearing data and target vectors of failure probability estimated by LR. After the training process, RVM is employed to predict failure probability of individual units of machine component. The performance of the proposed method is validated by applying the system to predict failure time of individual bearing based on simulation and experimental data. The result shows the plausibility and effectiveness of the proposed method, which can be considered as the machine degradation assessment model.     

Geothermal energy extraction using abandoned oil and gas wells: Techno-economic and policy review

Retrofitting depleted oil wells to extract geothermal energy is considered as one of the promising proposals to extend the overall economic life of oil and gas well. For successful implementation of this initiative, a comprehensive overview covering all aspects of geothermal energy extraction from abandoned oil well should be taken into account including technical, economic considerations as well as regulations and policies of respective local governments. Unfortunately, most reported studies have been focused only on one or two aspects, primarily on technical and economic aspects. Little or no study has focused on the policy sector. Moreover, these findings have been scattered, creating difficulties to extract essential information and dragging further development of the technology. This paper is therefore prepared with the objective to provide a comprehensive overview on the geothermal energy extraction from abandoned oil well, technical challenges in its implementation, economical consideration on the conversion of the well and government policy on energy especially geothermal energy and regulation on the utilization of abandoned oil well. To achieve this objective, extensive literature reviews are conducted with more attention given to recent studies on the field. Challenges on the development of this technology are discussed from technical, economic, and policy perspectives. Based on the identified challenges, required research and development as well as necessary policies for further advancement of this technology are outlined and discussed. By providing this comprehensive information, this review paper may serve as a good foundation and guidelines on the conversion of abandoned oil wells into geothermal energy wells.     

Case Study for a Cohesive Sediment Transport Model for Matagorda Bay, Texas, with Coupled ADCIRC 2D-Transport and SWAN Wave Models

Tidal current and wave forces are the primary factors causing agitation, suspension, and transport of littoral materials in a bay. This paper presents a study of the circulation patterns of the water and sediment fluxes in a real bay during ordinary natural weather conditions. A coupled hydrodynamic and wave model is developed to support the research. A two-dimensional parallel advanced circulation hydrodynamic model with an extended transport module is used to calculate the water circulation within the bay, while the simulating wave nearshore model is implemented to provide the wave parameter data. The month of March 2003 is selected to represent the test case for the sediment transport model in Matagorda Bay, Tex. The presence of wave action significantly, increases the amount of suspended sediment, and consequently, more deposited sediments occur around the ship channel, where shallow shoals are located. Comparison of the simulated deposited sediments in the Matagorda ship channel with the two selected points of historical dredging data of the bay gives a maximum difference of 22%. This result suggests the need for an extensive comparison study.