失去诚信必“穿帮”

一波未平一波又起,市场不断炸响惊雷。人们惊讶地发现,这些“爆雷”的主角竟然是一些行业的巨头,它们在耀眼的光环下不慎“穿帮”,露出可怕的獠牙。摊上了就没得选择,彼此都要直面。正如电视剧里的“穿帮”镜头,被敏锐的观众发现了,就无法掩盖了;镜头入眼了,也就无法假装没看见了。而“穿帮”背后不是演员的演技不够,而是导演低估了观众的智商.

过年啦

过年啦,小朋友们穿新衣,放鞭炮,好一派喜气洋洋的气氛.看,画面中,一个小朋友正在燃放鞭炮,另一个小朋友惊喜地看着炸响的鞭炮,紧紧地捂住耳朵,脸上露出了天真的笑容。画面中最引人注目的是那个颇具艺术范儿的'福'字,高高地倒挂在画面的上方,告诉人们'福到啦'.

Numerical Simulation of Dynamic Response and Collapse for Steel Frame Structures Subjected to Blast Load

The progressive collapse of steel frame structures under the blast load was investigated using LS-DYNA. The multi-material Eulerian and Lagrangian coupling algorithm was adopted. A flu-id-structure coupling finite element model was established which consists of Lagrange element for simulating steel frame structures and concrete ground, multiple ALE element for simulating air and TNT explosive material. Numerical simulations of the blast pressure wave propagation, struc-tural dynamic responses and deformation, and progressive collapse of a five-story steel frame structure in the event of an explosion near above ground were performed. The numerical analysis showed that the Lagrangian and Eulerian coupling algorithm gave good simulations of the shock wave propagation in the mediums and blast load effects on the structure. The columns subjected to blast load may collapse by shear yielding rather than by flexural deformation. The columns and joints of steel beam to column in the front steel frame structure generated enormous plastic defor-mation subjected to intensive blast waves, and columns lost carrying capacity, subsequently lead-ing to the collapse of the whole structure. The approach coupling influence between struc-tural deformation and fluid load well simulated the progressive collapse process of structures, and provided an effective tool for analyzing the collapse mechanism of the steel frame structure under blast load.

Dynamic responses of deep underground explosions based on improved Grigorian model

It is important to investigate the dynamic behaviors of deep rocks near explosion cavity to reveal the mechanisms of deformations and fractures. Some improvements are carried out for Grigorian model with focuses on the dilation effects and the relaxation effects of deep rocks, and the high pressure equations of states with Mie-Grüneisen form are also established. Numerical calculations of free field parameters for deep underground explosions are carried out based on the user subroutines which are compiled by means of the secondary development functions of LS-DYNA9703 D software. The histories of radial stress, radial velocity and radial displacement of rock particles are obtained, and the calculation results are compared with those of U.S. Hardhat nuclear test. It is indicated that the dynamic responses of free field for deep underground explosions are well simulated based on improved Grigorian model, and the calculation results are in good agreement with the data of U.S. Hardhat nuclear test. The peak values of particle velocities are consistent with those of test, but the waveform widths and the rising times are obviously greater than those without dilation effects. The attenuation rates of particle velocities are greater than the calculation results with classic plastic model, and they are consistent with the results of Hardhat nuclear test. The attenuation behaviors and the rising times of stress waves are well shown by introducing dilation effects and relaxation effects into the calculation model. Therefore, the defects of Grigorian model are avoided. It is also indicated that the initial stress has obvious influences on the waveforms of radial stress and the radial displacements of rock particles.

Numerical Simulation of Dynamic Response of an Existing Subway Station Subjected to Internal Blast Loading

In order to design and retrofit a subway station to resist an internal blast, the distribution of blast loading and its effects on structures should be investigated firstly. In this paper, the behavior of a typical subway station subjected to different internal blast Ioadings was analyzed. It briefly introduced the geometric characteristics and material constitutive model of an existing two-layer and three-span frame subway station. Then three cases of different explosive charges were consid- ered to analyze the dynamic responses of the structure. Finally, the maximum principal stress, dis- placement and velocity of the columns in the three cases were obtained and discussed. It con- cluded that the responses of the columns are sensitive to the charge of explosive and the distance from the detonation. It＇s also found that the stairs between the two layers have significant effects on the distribution of the maximum principal stress of the columns in the upper layer. The explicit dynamic nonlinear finite element software ANSYS/LS-DYNA was used in this study.

Simulation of the Response of Glass Window Under Blast Load

In the investigation of accidental explosion scene, the damage on the glass is one of the typi-cal traces which can be used to decide the characteristic of the explosion source. To analyze the re-sponse of glass under the blast load, a numerical model was developed. In the model, the brittleness glass model was adopted. A‘node release’method, which had some special merits compared with the erosion method was used to simulate the rupture of the glass In the calculation, several problems which play major role in the response of the glass were discussed. The velocity and the displacement of the glass fragment were two major factors. The numerical results are very helpful for the design and hazard assessment.

Production Optimization of Biodiesel from Frying Oil Waste to Reduce the Environmental Impacts

The objective of this study was to reduce the environmental impacts of used frying oil waste through the production of biodiesel. A 22 factorial planning has been used to evaluate the influences of alcohol/oil and reaction time on the biodiesel production yield. The optimal condition to produce the biodiesel has been found by use of the response surface methodology and analysis of variance to obtain the fitting model. This study was conducted in Campinas city, Brazil, where were collected the waste oil. An analysis of ecological cost also has been developed. Cooking oils collected from Campinas homes were mixed with ethanol in planned proportions （1：9, 1：7 and 1：5） and were transesterified at 60 ℃ and planned reaction times （30, 60 or 90 min）, in order to obtain biodiesel, using 0.1% NaOH as a catalyst. The results of the physical-chemical analyses demonstrated that the biodiesels obtained possessed characteristics close to those required by Brazilian standards. This fuel could be used in fleets of buses, trucks and machines, or even sold to fuel distributors, which results in a solving between US$0.8 and US$4.5 millions. Thus, Campinas would gain environmental credits and become a sustainable city.

Numerical Simulation of the Flat Ribbon Wound Explosion Containment Vessels Subjected to Internal Blast Loading

In order to constitute engineering design methods of the flat ribbon wound explosion containment vessels, the dynamic response of such vessels subjected to internal explosion loading is simulated using LS-DYNA3D. Three winding angles, 10°, 15°and 20°, are considered. It is shown that among ribbon vessels investigated, the center displacement of outermost ribbons of the vessel with 10°winding angle is the smallest under the same blast loading. The response of vessels loaded in inner core is local. From the center of the cylindrical shell to the bottom cover, the maximum strain gradually decreases. The ribbons are subjected to tension in the length direction and compression in the width direction. Blasting shock energy concentrates on where is close to center section of blasting. For comparison, numerical simulation of a monobloc thick-walled explosion containment vessel is also investigated. It can be found that the biggest deformation of the flat ribbon wound explosion containment vessels is bigger than that of the monobloc thick-walled explosion containment vessel in the center section of blasting under the same TNT. Numerical results are approximately in agreement with experimental ones. It is proved that the ribbon vessels have the valuable properties of ' leak before burst at worst' compared with the monobloc vessels through numerical simulation.

Optimizing rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 grown on waste frying oil using response surface method and batch-fed fermentation

Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2+ concentrations as the variables. Meanwhile, fed-batch fermentation experiments were conducted. The results show that the three variables are closely related to rhamnolipid production. The optimal cultivation conditions are of 6.4 g/L NaNO3 , 3.1 g/L MgSO4 at 32 ℃, with the maximum rhamnolipid production of 6.6 g/L. The results of fed-batch fermentation experiments show that feeding the oil in two batches can enhance rhamnolipid production. The best time interval is 72 h with the maximum rhamnolipid production of 8.5 g/L. The data are potentially useful for mass production of rhamnolipid on oil waste with this bacterium.

Experimental investigation on dynamic response of chamber to simulate deepwater explosive

Experimental investigation was conducted for the dynamic response of a real spherical explosive chamber that can simulate 200 m deepwater explosive loaded 10 g TNT equivalent.The vibration characteristics and dynamic strength of the chamber were analyzed by measuring the strain profiles of six characteristic points on the chamber.The research results revealed the rule of the dynamic response of the chamber on different explosive loads and static pressures.It provides references for the design and development of the chamber to simulate deepwater explosion.

A simplified model to predict blast response of CFST columns

In order to study the dynamic response of concrete-filled steel tube(CFST) columns against blast loads,a simplified model is established utilizing the equivalent single-degree-of-freedom(SDOF) method,which considers the non-uniform distribution of blast loads on real column and the axial load-bending moment(P-M) interaction of CFST columns.Results of the SDOF analysis compare well with the experimental data reported in open literature and the values from finite element modeling(FEM) using the program LS-DYNA.Further comparisons between the results of SDOF and FEM analysis show that the proposed model is effective to predict the dynamic response of CFST columns with different blast conditions and column details.Also,it is found that the maximum responses of the columns are overestimated when ignoring the non-uniformity of blast loads,and that neglecting the effect of P-M interaction underestimates the maximum response of the columns with large axial load ratio against close range blast.The proposed SDOF model can be used in the design of the blast-loaded CFST columns.

Dynamic Response of Structure under Blast Load

The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure. Firstly, the paper determines the parameters of the blast wave excited by a small charge explosion. The empirical formulas on the basis of our own experimental results are shown and used for the structure analysis. Evaluations of structures loaded by an explosion based on dynamic response in rotations round the central line of plate or beam systems during the dynamic load of this type is discussed in the paper and comparison of own limit values and published ones is presented. Blast loads typically produce very high strain rates in the range of 102 to 10-4 s-1. The effect of strain rate for concrete material is discussed. The formulas for increased compressive strength of concrete and steel reinforcement are presented. The ductility of structural members is influenced by the corresponding values under high strain rate of reinforcement, Damage to the structure is assessed accordingly firstly by the angle of rotation of the middle axis/surface, and secondly by the limit internal forces of the selected structure. The extreme nature of blast resistance makes it necessary to accept that structural members have some degree of inelastic response in most cases. This enables the application of structure dissipation using the ductility factor and increased of concrete strength. The limits are correlated with qualitative damage expectations. The methodology of dynamic response assessment and its application to the simple bridge structure is discussed.

春姑娘来了

春姑娘来了。她披着轻盈的薄纱,携着春风翩然而至,甜美的笑容融化了冰冻的小河,潺潺的流水像一曲快乐的音符,放飞着孩童爽朗的欢笑,沉寂的田野,增添了一抹赏心悦目的生机盎然。柔柔的风在空气中快速地弥漫,飞越高耸的山川,穿过寂寥的旷野,拂过湍急的溪流,仿佛定格在人生画卷上的一袭薄雾,朦胧缥缈、回味悠长。

Analyzing the service availability of mobile cloud computing systems by fluid-flow approximation

Mobile cloud computing （MCC） has become a promising technique to deal with computation- or data-intensive tasks. It overcomes the limited processing power, poor storage capacity, and short battery life of mobile devices. Providing continuous and on-demand services, MCC argues that the service must be available for users at anytime and anywhere. However, at present, the service availability of MCC is usually measured by some certain metrics of a real-world system, and the results do not have broad representation since different systems have different load levels, different deployments, and many other random factors. Meanwhile, for large-scale and complex types of services in MCC systems, simulation-based methods （such as Monte- Carlo simulation） may be costly and the traditional state-based methods always suffer from the problem of state-space explosion. In this paper, to overcome these shortcomings, fluid-flow approximation, a breakthrough to avoid state-space explosion, is adopted to analyze the service availability of MCC. Four critical metrics, including response time of service, minimum sensing time of devices, minimum number of nodes chosen, and action throughput, are def＇med to estimate the availability by solving a group of ordinary differential equations even before the MCC system is fully deployed. Experimental results show that our method costs less time in analyzing the service availability of MCC than the Markov- or simulation-based methods.

Study on dynamic response of multi-body structure under explosive driving

In this study, a complex multi-body structure was proposed, and the mechanism for the dynamic response of the structure under explosive driving was investigated by using the Lagrange equations of the second kind. An initial value subject to explosion loading was analyzed to develop the theoretical model of the dynamic response, and the centroid trajectory of three different structural shapes was solved. To verify the accuracy of the theoretical model, numerical simulation via finite element analysis within LS-DYNA and a dynamic experiment were conducted, and the consistent dynamic response process of the multi-body structure was obtained. In addition, the dynamic response time of the multi-body structure under different explosion loading conditions was calculated by the theoretical model, numerical simulation, and experimental investigation. It was found that the increased opening charge mass reduces the dynamic response time.

Dynamic Response of Warship Structure under Air Non-contact Explosion

The ship hull is simplified as a free beam with varying sections. Based on hydroelasticity and explosion mechanics theory,mechanical model and kinetic equation for hull girder vibration under non-contact explosion are established. The equation is solved by Wilson-θ algorithm. On the basis of the above principles,a structure kinetics analysis program is compiled. The dynamic response of supposed warship under air explosion is calculated conveniently and quickly. Under the explosion condition designed in the paper,the positive pressure period of non-contact explosion wave is much less than the natural periods of the first four modes of hull girder and the resonance of ship girder overall vibration can be avoided. The ratio of midship maximum moment to ultimate bearing strength under non-contact explosion accelerates with the increment of impact factor.