计算机通讯常存故障与维护探析

计算机的通讯功能,极大地方便了人与人之间的联系。但是,其中的常存故障往往会让人们的通讯中断,影响正常通讯。因此,计算机专业的学生要了解计算机通讯常存故障的检测步骤,研究计算机通讯的维护措施。

浩然正气 万古常存——纪念李大钊同志九十周年诞辰

李大钊同志生于一八八九年十月廿九日。大钊同志是我国革命早期的马克思主义思想家、卓越的无产阶级革命家、忠贞的共产主义战士。他全心全意为人民服务,把自已一生献给中国无产阶级革命事业的光辉形象,将永为人们所敬爱、所景慕、所钦仰。他的斗争生涯和革命业绩是难以尽述的,这里只作些片断叙述,以资纪念。

应对公路路面施工的常见问题与处理措施

随着近年来公路项目建设不断增多,正确处理好现有公路路面施工中的存在问题,是保证公路路面质量,提升企业形象的重要路径。本文针对公路路面施工中管理与技术两方面常见问题,分别概要指出现象及处理措施,供行内同事交流参考。

On the Existence of Periodic Solutions of a Class Nonlinear Differential Systems

One method to show the existence of ω-periodic system is given. This method is based on the ultimately boundedness of the solution of the systems. By using comparing theorem and discussing some one dimensional equations the main results are obtained.

A Generalized Upper and Lower Solution Method for Singular Discrete Boundary Value Problems

This paper presents new existence results for singular discrete boundary value problems. In particular our nonlinearity may be singular in its dependent variable and is allowed to change sign.

Chronic bile duct hyperplasia is a chronic graft dysfunction following liver transplantation

AIM: To investigate pathological types and influential factors of chronic graft dysfunction (CGD) following liver transplantation (LT) in rats. METHODS: The whole experiment was divided into three groups: (1) Normal group (n = 12): normal BN rats without any drug or operation; (2) SGT group (syngeneic transplant of BN-BN, n = 12): both donors and recipients were BN rats; and (3) AGT group (allogeneic transplant of LEW-BN, n = 12): Donors were Lewis and recipients were BN rats. In the AGT group, all recipients were subcutaneously injected by Cyclosporin A after LT. Survival time was observed for 1 year. All the dying rats were sampled, biliary tract tissues were performed bacterial culture and liver tissues for histological study. Twenty-one d after LT, 8 rats were selected randomly in each group for sampling. Blood samples from caudal veins were collected for measurements of plasma endotoxin, cytokines and metabonomic analysis, and faeces were analyzed for intestinal microflora. RESULTS: During the surgery of LT, no complications of blood vessels or bile duct happened, and all rats in each group were still alive in the next 2 wk. The long term observation revealed that a total of 8 rats in the SGT and AGT groups died of hepatic graft diseases, 5 rats in which died of chronic bile duct hyperplasia. Compared to the SGT and normal groups, survival ratio of rats significantly decreased in the AGT group (aP < 0.01, bP < 0.001, respectively). Moreover, liver necrosis, liver infection, and severe chronic bile duct hyperplasia were observed in the AGT group by H and E stain. On 21 d after LT, compared with the normal group (25.38 ± 7.09 ng/L) and SGT group (33.12 ± 10.26 ng/L), plasma endotoxin in the AGT group was remarkably increased (142.86 ± 30.85 ng/L) (both P < 0.01). Plasma tumor necrosis factor-α and interleukin-6 were also significantly elevated in the AGT group (593.6 ± 171.67 pg/mL, 323.8 ± 68.30 pg/mL) vs the normal (225.5 ± 72.07 pg/mL, 114.6 ± 36.67 pg/mL) and SGT groups (321.3 ± 88.47 pg/mL, 205.2 ± 53.06 pg/mL) (P < 0.01). Furthermore, Bacterial cultures of bile duct tissues revealed that the rats close to death from the SGT and AGT groups were strongly positive, while those from the normal group were negative. The analysis of intestinal microflora was performed. Compared to the normal group (7.98 ± 0.92, 8.90 ± 1.44) and SGT group (8.51 ± 0.46, 9.43 ± 0.69), the numbers of Enterococcus and Enterobacteria in the AGT group (8.76 ± 1.93, 10.18 ± 1.64) were significantly increased (both aP < 0.01, bP < 0.05, respectively). Meanwhile, compared to the normal group (9.62 ± 1.60, 9.93 ± 1.10) and SGT group (8.95 ± 0.04, 9.02 ± 1.14), the numbers of Bifidobacterium and Lactobacillus in the AGT group (7.83 ± 0.72, 8.87± 0.13) were remarkably reduced (both aP < 0.01, bP < 0.05, respectively). In addition, metabonomics analysis showed that metabolic profiles of plasma in rats in the AGT group were severe deviated from the normal and SGT groups. CONCLUSION: Chronic bile duct hyperplasia is a pathological type of CGD following LT in rats. The mechanism of this kind of CGD is associated with the alterations of inflammation, intestinal barrier function and microflora as well as plasma metabolic profiles.

Simulation of strain induced abnormal grain growth in aluminum alloy by coupling crystal plasticity and phase field methods

A mesoscale modeling methodology is proposed to predict the strain induced abnormal grain growth in the annealing process of deformed aluminum alloys. Firstly, crystal plasticity finite element(CPFE) analysis is performed to calculate dislocation density and stored deformation energy distribution during the plastic deformation. A modified phase field(PF) model is then established by extending the continuum field method to consider both stored energy and local interface curvature as driving forces of grain boundary migration. An interpolation mapping approach is adopted to transfer the stored energy distribution from CPFE to PF efficiently. This modified PF model is implemented to a hypothetical bicrystal firstly for verification and then the coupled CPFE-PF framework is further applied to simulating the 2D synthetic polycrystalline microstructure evolution in annealing process of deformed AA3102 aluminum alloy.Results show that the nuclei with low stored energy embedded within deformed matrix tend to grow up, and abnormal large grains occur when the deformation is close to the critical plastic strain, attributing to the limited number of recrystallized nuclei and inhomogeneity of the stored energy.

Existence of Periodic Solutions About One Class Differential Equation

We discuss the existence and the number of periodic solutions of differential equation dx/dt=A_1(t)x+A_2(t)x^2+A_3(t)x^3/a_0(t)+a_1(t)x+a_2(t)x^2 (1) where A_i(t), a_j(t) (i=1,2,3;j=0,1,2) are continuous periodic functions. The results of this paper extend the work of paper [1].

A Class of Strongly Nonlinear Singular Perturbed Boundary Value Problems

In this paper, a class of strongly nonlinear singular perturbed boundary value problems are coasidered by the theory of differential inequalities and the correction of boundary layer, under which the existence of solution is proved and the uniformly valid asymptotic expansions is obtained as well.

Weak Noether Symmetry and non-Noether Conserved Quantities for General Holonomic Systems

A new kind of weak Noether symmetry for a general holonomic system is defined in such a way that themethods to construct Hojman conserved quantity and new-type conserved quantity are given.It turns out that weintroduce a new approach to look for the conserved laws.Two examples are presented.

Screening Effect in Charge Qubit

We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr6hlich transformation in the qubit-cavity-resonator system, we calculate the decoherenee factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.

Linking Groundwater Quality and Quantity： An Assessment of Satellite-Based Groundwater Storage Anomalies from GRACE against Ground Measurements of Contaminants in California

Groundwater comprises a large portion of irrigation for California＇s agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the same time, contaminants from fertilizers and pesticides are infiltrating into the groundwater, becoming increasingly concentrated as water is extracted. It compared space-based observations of groundwater anomalies from California＇s San Joaquin Valley using the GRACE （gravity recovery and climate experiment） against measurements of 42 organic and inorganic chemicals from 41,667 wells in the valley from 2003 to 2010. It compared Arsenic, Boron, Cadmium, Chloride, Selenium, Trichloroethylene, and TDS （total dissolved solid） concentrations with the groundwater storage anomaly from 2003 to 2010. The results show strong correlations for groundwater depletion against increasing chloride （r2= 0.78, p 〈 0.05） and boron （r2 = 0.88, p 〈 0.05）. This indicates increasing contaminant concentrations while groundwater was depleting over the last eight years. Solubilization by complexation with Cl, CO3 and/or organic chelates may account for the increasing concentration of some heavy metals when groundwater depletion occurs. These results are the first to link space-based groundwater mass change with groundwater contaminant concentration change.

Design and Fabrication of the Magnets for BEPCⅡ Project

The BEPCⅡis the upgrade project of the Beijing Electron Positron Collider(BEPC).According to the BEPCⅡdouble ring design scheme,a new ring will be added in the existing BEPC tunnel.The machine will provide electron and positron beams with an energy range from 1.0GeV to 2.1GeV for high energy physics research,and an electron beam of 2.SGeV,250mA for synchrotron radiation.So actually there are three storage rings for the BEPCⅡmachine.Due to the limited space of the existing BEPC tunnel and the requirement of high luminosity,the antechamber type vacuum chamber is used,that makes the BEPCⅡmagnets'design and fabrication very difficult.In the paper the general features of the design and fabrication of several kinds of main magnets for the BEPCⅡstorage ring and its interaction region are introduced.And the magnetic field measurement results are presented.

Coexisting Phenomena of Surge and Rotating Stall in an Axial Flow Compressor

The unsteady inner flow structure of a single-stage axial flow compressor under the coexisting conditions of surge and rotating stall was experimentally investigated via detailed measurements of the unsteady characteristics and the internal flow velocity fluctuations. The main relevant feature of the tested compressor is a shock tube with a capacity tank connected in series to the compressor outlet through slits and a concentric duplex pipe: surge and rotating stall can both be generated by connecting the shock tube. Research attention is focused on the unsteady behavior of a rotating stall during the surge cycle. The size of the rotating stall cell during the recovery process of an irregular surge cycle was experimentally determined by the circumferential flow velocity fluctuations ahead of the rotor blade. The results suggested that the size of the rotating stall cell at the switching point of the performance curve between large and small cycles is considered to be the key parameter in determining the following surge cycle. In addition, the surge cycle is largely influenced by the unsteady behavior of the rotating stall cell.

Generalized Steiner Triple Systems with Group Size Ten

Generalized Steiner triple systems, GS(2, 3, n, g) are equivalent to (g+1)-ary maximum constant weight codes (n, 3,3)s. In this paper, it is proved that the necessary conditions for the existence of a GS(2,3, n, 10), namely, n ≡ 0,1 (mod 3) and n ≥ 12, are also sufficient.