Analysis of blast-induced ground vibration under surface explosion

The blasting operation is vital in the construction of tunnels and channels or in mining when encountering hard geological environments to facilitate the progress of a project. The level and range of damage due to the blast are affected by the energy of shock waves generated after explosion. The control of seismic damage is a major issue in blasting engineering and cannot be neglected. The stratum layer or buildings on the earth’s surface can be damaged when blasting-induced vibration strength exceeds the allowed range. In order to reduce the degree of damage, the patterns of blasting vibration must be studied and controlled. Therefore, the propagation characteristics of shock waves on the earth’s surface are important factors to be studied before the planning and designing of a project. This paper adopted a mutual verification method between the blasting experiment and numerical analysis results for verifying the reliability of numerical simulation based on experimental data. The numerical analysis method analyzed the dynamic mechanical behavior of blasting vibration using the finite element method. The LS-DYNA program was used to simulate TNT explosive and surface contact blasting in semi-infinite space and in propagation of the resulting seismic waves. The propagation characteristics, represented by temporal and spatial changes of surface acceleration, were investigated. The analysis results showed that post-explosion dynamic characteristics of the earth’s surface simulated by finite element method yielded promising simulation results. In addition, the propagation characteristics of stress waves were observed from the dynamic mechanical behavior of surface acceleration after explosion. That is, the maximum main stress presented a pattern of progressive attenuation with increasing distance from the blasting source. The results are able to provide reference for the protection of engineering structures from blasting vibration damages

Analysis of blasting vibration wave propagation based on finite element numerical calculation and experimental investigations

Seismic waves created during explosions are transmitted in an outward direction via the surrounding medium, creating a seismic effect that compromises the security of facilities. The energy released during explosions forms dynamic pressure, which creates gas pressure-induced blast waves that cause the ground to vibrate. The damage extent and influence of a blast are dependent on the energy released by the blast shock waves. Blast waves influence the stability of materials. Therefore, controlling vibration hazards is imperative in ensuring material security. This study investigated the effect of explosion-induced vibrations on the surface of a leveled landform. Changes in dynamic load over time were analyzed by conducting numerical simulations and actual onsite experiments. The Multi-Material Arbitrary Lagrangian-Eulerian algorithm were employed to develop a structural model for coupling fluid with solid grids, which was used to analyze the ground acceleration induced by the blasting effect. The results were used to determine the appropriate distance from which vibration reduction, disaster prevention, and safety protection can be achieved

A Bandit Approach to Online Pricing for Heterogeneous Edge Resource Allocation

Edge Computing (EC) offers a superior user experience by positioning cloud resources in close proximity to end users. The challenge of allocating edge resources efficiently while maximizing profit for the EC platform remains a sophisticated problem, especially with the added complexity of the online arrival of resource requests. To address this challenge, we propose to cast the problem as a multi-armed bandit problem and develop two novel online pricing mechanisms, the Kullback-Leibler Upper Confidence Bound (KL-UCB) algorithm and the Min-Max Optimal algorithm, for heterogeneous edge resource allocation. These mechanisms operate in real-time and do not require prior knowledge of demand distribution, which can be difficult to obtain in practice. The proposed posted pricing schemes allow users to select and pay for their preferred resources, with the platform dynamically adjusting resource prices based on observed historical data. Numerical results show the advantages of the proposed mechanisms compared to several benchmark schemes derived from traditional bandit algorithms, including the Epsilon-Greedy, basic UCB, and Thompson Sampling algorithms

Evidence of d-phenylglycine as delivering tool for improving l-dopa absorption

<p>Abstract</p> <p>Background</p> <p><it>l</it>-Dopa has been used for Parkinson's disease management for a long time. However, its wide variety in the rate and the extent of absorption remained challenge in designing suitable therapeutic regime. We report here a design of using <it>d</it>-phenylglycine to guard <it>l</it>-dopa for better absorption in the intestine via intestinal peptide transporter I (PepT1).</p> <p>Methods</p> <p><it>d</it>-Phenylglycine was chemically attached on <it>l</it>-dopa to form <it>d</it>-phenylglycine-<it>l</it>-dopa as a dipeptide prodrug of <it>l</it>-dopa. The cross-membrane transport of this dipeptide and <it>l</it>-dopa via PepT1 was compared in brush-boarder membrane vesicle (BBMV) prepared from rat intestine. The intestinal absorption was compared by <it>in situ </it>jejunal perfusion in rats. The pharmacokinetics after i.v. and p.o. administration of both compounds were also compared in Wistar rats. The striatal dopamine released after i.v. administration of <it>d</it>-phenylglycine-<it>l</it>-dopa was collected by brain microdialysis and monitored by HPLC. Anti-Parkinsonism effect was determined by counting the rotation of 6-OHDA-treated unilateral striatal lesioned rats elicited rotation with (+)-methamphetamine (MA).</p> <p>Results</p> <p>The BBMV uptake of <it>d</it>-phenylglycine-<it>l</it>-dopa was inhibited by Gly-Pro, Gly-Phe and cephradine, the typical PepT1 substrates, but not by amino acids Phe or <it>l</it>-dopa. The cross-membrane permeability (Pm*) determined in rat jejunal perfusion of <it>d</it>-phenylglycine-<it>l</it>-dopa was higher than that of <it>l</it>-dopa (2.58 ± 0.14 vs. 0.94 ± 0.10). The oral bioavailability of <it>d</it>-phenylglycine-<it>l</it>-dopa was 31.7 times higher than that of <it>l-</it>dopa in rats. A sustained releasing profile of striatal dopamine was demonstrated after i. v. injection of <it>d</it>-phenylglycine-<it>l</it>-dopa (50 mg/kg), indicated that <it>d</it>-phenylglycine-<it>l</it>-dopa might be a prodrug of dopamine. <it>d</it>-Phenylglycine-<it>l</it>-dopa was more efficient than <it>l-</it>dopa in lowering the rotation of unilateral striatal lesioned rats (19.1 ± 1.7% vs. 9.9 ± 1.4%).</p> <p>Conclusion</p> <p>The BBMV uptake studies indicated that <it>d</it>-phenylglycine facilitated the transport of <it>l</it>-dopa through the intestinal PepT1 transporter. The higher jejunal permeability and the improved systemic bioavailability of <it>d-</it>phenylglycine-<it>l</it>-dopa in comparison to that of <it>l</it>-dopa suggested that <it>d-</it>phenylglycine is an effective delivery tool for improving the oral absorption of drugs like <it>l</it>-dopa with unsatisfactory pharmacokinetics. The gradual release of dopamine in brain striatum rendered this dipeptide as a potential dopamine sustained-releasing prodrug.</p

タイワン ノ ニホンゴ ガッカ ノ ダイガクインセイ ノ ニホンゴ トノ カカワリ ニツイテノ ホウモン チョウサ : シンガクマエ カラ ソツギョウゴ マデ

This study interviewed 20 postgraduate students during April 2010 to July 2011, and concluded the following: There are few students desire to study in Japanese Department as a freshman, but most of them decided to do higher study in Japanese Gratuate Schools in their senior year. Many of the interviewees claimed that they would find a job if not being accepted by a postgraduate school. The criteria for students’ sections on specific postgraduate schools included whether it is the students’ alma mater, the policy of the postgraduate school, and the geological location of the school. Most students acquired the circumstances for the school, while some of them pointed out the difference between those stated on the webpage and the reality. Although with heavy study load, most students gained capability, not only in being awarded the degree, but also being promoted with logic training and data acquisition. Most interviewees agreed that the postgraduate study is an important stage in their life career

Multi-axial creep-fatigue life prediction considering history-dependent damage evolution : a new numerical procedure and experimental validation

In this paper, a new numerical procedure based on a cycle-by-cycle analysis has been constructed for creep-fatigue behavior and life prediction of high-temperature structures under multi-axial stress states. Within this framework, a modified unified viscoplastic constitutive model with isotropic hardening and modified kinematic hardening rules is developed to simulate the cycle-by-cycle stress-strain responses.Moreover, the newly constructed creep-fatigue approach calculates fatigue and creep damage variables using the critical plane method (CPM) and the modified strain energy density exhaustion (SEDE) model, respectively. The multi-axial ductility factor and elastic follow-up factor are also introduced into the modified SEDE model to accommodate the special multi-axial and mixed controlled modes, which are widely existed in practical structures. In order to validate the feasibility of the proposed numerical procedure, a series of creep-fatigue tests of notched specimens made from nickel-based GH4169 superalloy were carried out at 650 °C. The predicted numbers of cycles to crack initiation agree well with the experimental data. Evidence of crack initiation under various loading conditions was observed via the electron backscatter diffraction (EBSD) technique, indicating location-dependent crack initiations depending on loading conditions. In detail, the crack initiation sites shifting from surface to subsurface with increasing hold times can be well simulated by the proposed numerical procedure due to a reasonable description of the creep- fatigue damage evolution

General Versus Spinal Anesthesia: Which is a Risk Factor for Octogenarian Hip Fracture Repair Patients?

SummaryBackgroundMost studies have shown no difference between the two types of anesthesia administered to hip fracture patients. This study compared postoperative morbidity and mortality in octogenarian patients who received either general or spinal anesthesia for hip fracture repair.MethodsWe retrospectively analyzed the hospital records of 335 octogenarian patients who received hip fracture repair in our teaching hospital between 2002 and 2006. A total of 167 and 168 patients received general and spinal anesthesia, respectively. Morbidity, mortality, and intraoperative and preoperative variables were compared between groups.ResultsThere were no mortality differences between spinal and general anesthesia groups. However, the overall morbidity was greater in the general anesthesia group than in the spinal anesthesia group (21/167 [12.6%] vs. 9/168 [5.4%]; p = 0.02). Respiratory system-related morbidity was also higher in the general anesthesia group than in the spinal anesthesia group (11/167 [6.6%] vs. 3/168 [1.8%]; p = 0.03). Logistic regression analysis revealed two significant predictors of postoperative morbidity: anesthesia type (general; odds ratio, 2.39) and preexisting respiratory diseases (odds ratio, 3.38).ConclusionGeneral anesthesia increased the risk of postoperative morbidity in octogenarian patients after hip fracture repair, and patients with preexisting respiratory diseases were especially vulnerable. Spinal anesthesia is strongly recommended in such individuals