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Flexural Property of String Beam of Pre-Stressed Glulam Based on Influence of Regulation and Control
Get PDFApplying pre-stress in glulam beam can reduce its deformation and make full use of the compressive strength of wood. However, when the glulam with low strength and the pre-stressed steel with high strength form combined members, materials of high strength can’t be fully utilized. Therefore, this study puts forward the idea of regulating and controlling string beam of pre-stressed glulam. By regulating and controlling the pre-stress, a part of the load borne by the wood is allocated to the pre-stressed tendon, which is equivalent to completing a redistribution of internal force, thus realizing the repeated utilization of the wood strength and the full utilization of the strength of the high-strength pre-stressed tendon. The bending experiments of 10 beams under 5 working conditions are carried out. The failure mode, bearing capacity and deformation of the beams are analyzed. The results show that 90% of beams are deformed under compression. The ultimate load of the regulated and controlled beam is obviously larger than that of the unregulated beam, and the ultimate load of the beam increases with the increase of the degree of regulation and control. Compared with that of the unregulated beams, the ultimate load of beams regulated by 7.5%-30% increases by 25.42%-65.08%, and the regulated and controlled effect is obvious. With the increase of the regulation and control amplitude of pre-stress, the stiffness of string beam of pre-stressed glulam increases. In addition, with the increase of the regulation and control amplitude, the compression height of the beam increases before the failure, and it reaches the state of full-section compression at the time of failure, giving full play to the compressive property of the glulam. At the end of the experiment, the constitutive relation which can reflect the anisotropy of the wood is established combined with the experimental data. The finite element analysis of the beam under 7 working conditions is carried out by using ABAQUS finite element program, and the influence of the regulation and control amplitude on the stress distribution and ultimate bearing capacity of the beam is discussed
T Application of MES System in the Safety Management of Offshore Oil and Gas Fields
Get PDFIn order to solve the problem of data island in the safety management of offshore oil and gas fields, take full advantage of data for subsequent analysis and development, and support production safety management of oil and gas fields, the MES, which is maturely applied in manufacturing and downstream production of CNOOC (China National Offshore Oil Corporation), is introduced by the petroleum administration at the eastern South China sea. The system adopts the real-time database and relational database to collect the scattered structured data, such as evidence information of offshore oil and gas production facilities personnel, on-site hidden danger information and incident investigation report. Then a unified secure data center platform is established for every operating area and production site, and the critical safety data of production sites can be centrally managed. This system has the functions of lawful real-time supervision of personnel qualification, online supervision and trend analysis of hidden dangers, and centralized management and sharing of incident investigation report. By applying the MES system in security management, the process of safety service becomes standardized and modularized, the management process becomes normalized, and the efficiency and effect of overall management is improved
Research on Protecting Information Security Based on the Method of Hierarchical Classification in the Era of Big Data
No full textBig data is becoming increasingly important because of the enormous information generation and storage in recent years. It has become a challenge to the data mining technique and management. Based on the characteristics of geometric explosion of information in the era of big data, this paper studies the possible approaches to balance the maximum value and privacy of information, and disposes the Nine-Cells information matrix, hierarchical classification. Furthermore, the paper uses the rough sets theory to proceed from the two dimensions of value and privacy, establishes information classification method, puts forward the countermeasures for information security. Taking spam messages for example, the massive spam messages can be classified, and then targeted hierarchical management strategy was put forward. This paper proposes personal Information index system, Information management platform and possible solutions to protect information security and utilize information value in the age of big data
Digital Continuity Guarantee Method of Urban Construction Archives Based on Risk Management
No full textWith the broad application of information technology in urban infrastructure, urban construction has entered the stage of a smart city, forming many electronic records in urban construction. These electronic records play a vital role in the maintenance of urban infrastructure. However, electronic records often change in the process of urban construction. How to preserve the electronic records of urban construction became a significant challenge. In response to this problem, this paper proposes the use of risk-based management techniques to ensure the digital continuity, authenticity, integrity, and availability of electronic record
OpenIFEM: A High Performance Modular Open-Source Software of the Immersed Finite Element Method for Fluid-Structure Interactions
No full textWe present a high performance modularly-built open-source software - OpenIFEM. OpenIFEM is a C++ implementation of the modified immersed finite element method (mIFEM) to solve fluid-structure interaction (FSI) problems. This software is modularly built to perform multiple tasks including fluid dynamics (incompressible and slightly compressible fluid models), linear and nonlinear solid mechanics, and fully coupled fluid-structure interactions. Most of open-source software packages are restricted to certain discretization methods; some are under-tested, under-documented, and lack modularity as well as extensibility. OpenIFEM is designed and built to include a set of generic classes for users to adapt so that any fluid and solid solvers can be coupled through the FSI algorithm. In addition, the package utilizes well-developed and tested libraries. It also comes with standard test cases that serve as software and algorithm validation. The software can be built on cross-platform, i.e., Linux, Windows, and Mac OS, using CMake. Efficient parallelization is also implemented for high-performance computing for large-sized problems. OpenIFEM is documented using Doxygen and publicly available to download on GitHub. It is expected to benefit the future development of FSI algorithms and be applied to a variety of FSI applications
Suppression of Ambipolar Conduction in Schottky Barrier Carbon Nanotube Field Effect Transistors: Modeling, Optimization Using Particle Swarm Intelligence, and Fabrication
No full textA mathematical model and experimental analysis of the impact of oxide thickness on the ambipolar conduction in Schottky Barrier Carbon Nanotubes (CNTs) Field Effect Transistor (SB CNTFETs) is presented. Suppression of ambipolar conduction in SB CNTFETs is imperative in order to establish them as the future of IC technology. The ambipolar nature of SB CNTFETs leads to a great amount of leakage current. Employing a gate oxide dielectric of thickness, tox~50 nm suppresses the ambipolar behavior. In an SB CNTFET, it is the electric field at the source/drain contacts that control the conductance and the band bending length at the contacts is defined by tox. Therefore, tox is the prime parameter that influences the width of the Schottky barrier and the current in the subthreshold region. Due to the wide SB, there is a loss in on-current due to tunneling, but the current due to thermionic emission is increased by employing a high-κ dielectric such as Zirconium dioxide (ZrO2). This work proposes an approach to suppress ambipolar behavior in SB CNTFETs without decreasing the on current. The thickness and dielectric constant of the gate oxide are optimized using the particle swarm optimization (PSO) algorithm to achieve suppression of ambipolar conduction without any loss in on-current. The proposed SB CNTFET was modeled using Verilog-A. Experimental demonstration of the suppression of ambipolar property is also presented. Two SB CNTFETs are fabricated using high-κ dielectric such as ZrO2 with different thickness. A device with thin (~5 nm) gate oxide and another device with thick (~50 nm) gate oxide were fabricated. From the experimental results, it is observed that the device with the thin gate oxide exhibited ambipolar characteristics and the device with the thick gate oxide did not exhibit ambipolar characteristics. The increase in thickness, tox, ensures suppression of ambipolar behavior
Thermal and Mechanical Properties of Thermoplastic Starch and Poly(Vinyl Alcohol-Co-Ethylene) Blends
No full textThe interest in thermoplastic starch (TPS) as a substitute material to replace conventional thermoplastics continues especially due its biodegradability, availability, low cost and because it is obtained from renewable sources. However, its poor mechanical properties and its high sensitivity to humidity have limited its use in several applications. Here, the copolymer poly (ethylene-co-vinyl alcohol) (EVOH), with two different ethylene contents, 27 and 44 mol% were blended with TPS by extrusion in order to overcome these limitations. The obtained blends were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical tensile testing, Scanning Electron Microscopy (SEM) and moisture absorption test. The addition of EVOH copolymer did not significantly changed the thermal stability of TPS, however it increased the tensile strength in 65% when compared to TPS. The morphology of the blends did not showed two distinct phases, an indication of miscibility or partial miscibility of the components. A decrease of moisture absorption was obtained by the addition of EVOH and is more pronounced for the EVOH with 44% of ethylene
Green Nanocomposites Made With Polyvinyl Alcohol and Cellulose Nanofibers Isolated From Recycled Paper
No full textThis paper reports green nanocomposites made by blending polyvinyl alcohol (PVA) with cellulose nanofiber (CNF) isolated from recycled deinked copy/printing paper (DIP). The reinforcement effect of DIPCNF in the nanocomposites is compared with other CNFs isolated from native cotton and hardwood by means of TEMPO-oxidation. The prepared PVA-CNF nanocomposites are characterized in terms of morphology, chemical interaction, structural, thermal and mechanical properties. X-ray diffraction and Fourier transform infrared spectroscopy confirm the reinforcing ability of cellulose nanofibers into PVA. By blending CNFs into PVA matrix, the thermal stability of the nanocomposites is improved and DIPCNF shows similar enhancement effect with COCNF and HWCNF. The prepared nanocomposites exhibit 50% Young’s modulus improvement by adding 6% of CNF and DIPCNF exhibits similar enhancement of the mechanical properties to COCNF and HWCNF in the nanocomposites. This indicates that the use of DIPCNF is beneficial for environment protection, resource retaining and save energy in comparison with COCNF and HWCNF
<i>Trypanosoma rangeli:</i> growth in mammalian cells <i>in vitro</i> and action of a repositioned drug (17-AAG) and a natural extract (<i>Artemisia sp</i>. essential oil)
No full textTrypanosoma rangeli and T. cruzi are both parasitic unicellular species that infect humans. Unlike T. cruzi,
the causative agent of Chagas disease, T. rangeli is an infective and non-pathogenic parasite for humans, but pathogenic
for vectors from the Rhodnius genus. Because both species can coexist in different hosts and overlap their infective
cycles but very little is known about the infection of T. rangeli in mammalian cells, we decided to characterize both the
development of this parasite in cell culture and the effect of therapeutic agents with potential trypanocidal action on
it. We found that T. rangeli exhibits a cycle of infection in Vero cells similar to that for T. cruzi and that the repurposed
drug, 17-AAG, and the natural extract Artemisia sp. essential oil produce a toxic effect on epimastigotes showing
a trypanocidal action from the fifth day of culture. Both treatments also affected the infection of trypomastigotes
and reduced the capacity of replication of amastigotes of T. rangeli. Since T. cruzi / T. rangeli coinfection cases have
been reported, the finding of drugs with potential activity against both species could be significant in the future.
Furthermore, studies of susceptibility of both species to drugs could also help to know the different mechanisms of
pathogenicity in humans displayed by T. cruzi that are absent in T. rangeli</i
Clustering of halophytic species from Cyprus based on ionic contents
No full textThis paper presents the work conducted on the
chemical constituents of some common and widely distributed
halophyte taxa from Cyprus with the aim that these studies will
help in the evaluation of halophytes for different economical
purposes. The plant species of Crithmum maritimum L., Limbarda
crithmoides (L.) Dumort, Atriplex portulacoides L., Salsola kali L.,
Atriplex halimus L., Limonium oleifolium Mill., L. meyeri (Boiss.)
Kuntze; and Tetraena alba (L.f.) Beier & Thulin were collected
in the middle of July. The shoot tissue and leaf samples were
collected from the natural habitats and left for drying under air
circulation followed by placing them in oven at 60 °C for 96
hours. The material was crushed using mortar and pestle and
subjected to an analysis of macro- and micro-nutrients and
biochemical compounds. K+/Na+ in the leaf tissues of the dicot
species showed relatively high values depicting their behavior
as Na+ includes but very low Cl- levels were recorded. Out of
the species investigated here in 4 TFAA content was rather high.
Values ranging from 0.5% to 1% dry weight were exhibited in one
species. However, only 3 species showed very low TFAA values.
Later may be due to low nitrogen availability in their environment.
The phenetic analyses of eight halophyte species performed on
the data matrix using Ntsys-pc program version 2.1 revealed
that, cluster analysis of the overall results obtained here leads to
2 clusters. This discrimination appears to be as a result of their
different abilities to accumulate either proline or glycine betaine