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Background: With the continuous penetration of renewable energy in modern power systems, the problem of excessive frequency deviation of power systems, which is caused by the integration of wind power into electricity grids, needs to be solved urgently. Objective: Make up for frequency fluctuations when AC systems fail, improve the frequency characteristics of main system networks, and reasonably distribute unbalanced power. Methods: According to the principle of active power distribution, a frequency division coordinated control strategy that uses low-pass filter control to divide power fluctuations into highfrequency fluctuations and low-frequency fluctuations is proposed. High-frequency fluctuations are attached to the wind farm side, and low-frequency fluctuations are attached to the DC system to realize frequency division control. Result: The simulation results showed that the coordination of the frequency division control of the wind farm and flexible DC system could effectively reduce the main grid’s frequency fluctuations, which are caused by the AC system failure, and improve the stable operation ability of the AC and DC systems. Conclusion: The frequency division control can overcome the unbalanced power distribution caused by traditional droop control, reduce the frequency deviation of the AC system, realize frequency autonomy, and enhance system robustness.

The paper takes one submersible linear motor double-acting pump as a research object. A relationship of linear motor output capability and its controls parameters is concluded by building a model. The oil production system control rule is researched by optimizing voltage, frequency and other control parameters. The results showed that a way by adjusting the output voltage and frequency can improve output capability of linear motor effectively and expand the oil production depth and application range of oil production system. Changing the maximum speed of the actuator through frequency has a great influence on the change of the maximum thrust required by the linear motor, because the change of speed has a great influence on the resistance along the path. The submersible linear motor double-acting pump oil production system is more suitable for deep Wells with less oil production.

By using the waveform measurements and the least square method, the duration of transient level, and the duration of transient decreasing segment of aircraft DC transient signal are evaluated precisely. The evaluation courses and some technical problems are discussed in detail, the uncertainty analysis both of the durations are presented. Some test results have proved the effectiveness and practicability of the method. It could be applied to the characteristic and performance evaluation of aircraft DC transient signal waveform generators.

The development of spiral wave in a two-dimensional square array due to partial ion channel block (Potassium, Sodium) is investigated, the dynamics of the node is described by Hodgkin—Huxley neuron and these neurons are coupled with nearest neighbor connection. The parameter ratio xNa (and xK), which defines the ratio of working ion channel number of sodium (potassium) to the total ion channel number of sodium (and potassium), is used to measure the shift conductance induced by channel block. The distribution of statistical variable R in the two-parameter phase space (parameter ratio vs. poisoning area) is extensively calculated to mark the parameter region for transition of spiral wave induced by partial ion channel block, the area with smaller factors of synchronization R is associated the parameter region that spiral wave keeps alive and robust to the channel poisoning. Spiral wave keeps alive when the poisoned area (potassium or sodium) and degree of intoxication are small, distinct transition (death, several spiral waves coexist or multi-arm spiral wave emergence) occurs under moderate ratio xNa (and xK) when the size of blocked area exceeds certain thresholds. Breakup of spiral wave occurs and multi-arm of spiral waves are observed when the channel noise is considered.

Objective To explore the pharmacologic effects of Chinese medicine Bushen Huayu Jiedu Compound Recipe (补肾化瘀解毒复方, BSHYJDR) in drug-resistance cells of lung cancer.

In this paper, a scheme of spatial perturbation is introduced into a class of excitable media, which are described by two-dimensional partial-differential equation models. Inertial acentric force (or centripetal force), which is generated by circumgyrating the whole system vs. a right axis, is used to disturb the system. The whole system becomes homogeneous as soon as the spatial perturbation is imposed on even when the noise is in consideration. The principle of this scheme is confirmed based on the theory of hopf bifurcation and numerical simulation.

Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.

During the non-frost season, the condensation of dew makes Nostoc flagelliforme Born. et Flah., a highly drought-tolerant terrestrial cyanobacterium, frequently undergo rehydration-dehydration. Rehydration begins in the dark at night. After rewetting in the dark, photochemical activity and the structure of photosystem (PS) II were not recovered at all; the structure of PSI, energy transfer in phycobilisomes, and energy transfer from phycobilisomes to PSI were recovered within 5 min, as in the light. The recovery of energy transfer from phycobilisomes to PSII was light dependent and energy transfer from phycobilisomes to PSII was only partially recovered in the dark. These results suggest that the two-trigger control (water and light) of photo synthetic recovery may make N. flagelliforme avoid unnecessary energy consumption and, at the same time, the partial recovery of energy transfer from phycobilisomes to PSII in the dark could help N. flagelliforme accumulate more photosynthetic products during the transient period of rehydration-dehydration. (Managing editor: Ping HE)

The Fitzhugh?Nagumo (FHN) equation is used to generate spiral and spatiotemporal chaos. The weak Lorenz chaotic signal is imposed on the system locally and globally. It is found that for the right chaotic driving signal, spiral and spatiotemporal chaos can be suppressed. The simulation results also show that this anti-control scheme is effective so that the system emerges into the stable states quickly after a short duration of chaotic driving (about 50 time units) and the continuous driving keeps the system in a homogeneous state.

The development of advanced technology based on the interaction of high current pulsed electron beam (HCPEB) with solid materials is very important at present time [R. Stark, J. Christiansen, et al., IEEE Trans. Plasma Sci. 23 (3) (1995) 258–264; T. Witke, A. Lenk, B. Schultrich, IEEE Trans. Plasma Sci. 24 (1) (1996) 61–62]. When the concentrated electron flux are acting on a material, superfast processes such as heating, melting, and solidification, as well as dynamic stresses induced in the processes impart surface layer with improved physical, chemical and mechanical properties unattainable with conventional surface treatment methods. This paper reports on an investigation on pure aluminum treated by “Nadezhda-2” HCPEB device. The extreme surface is melted to a depth of about 1 μm at the input energy density of 3 J/cm 2 . Craters, micrometers in size, are formed in the melted surface. Vacancy and dislocations are significantly increased near the surface as a result of the electron bombardment. Based on the microhardness distribution measured on the cross-section, it has been established that the thickness of the modified layer is several hundreds of micrometers beneath the surface, significantly greater than that of the heat-affected zone. The experimental results are compared with those obtained by solving numerically the heat and stress equations, with finite difference and finite element methods, taking into account of the processes of melting and changing of physics parameters related to changing temperature. Satisfactory agreement between experimental and theoretical data is obtained.

Cross-sections for (n, 2n) reactions have been measured on stannum isotopes at the neutron energies of 13.5 to 14.6 MeV using the activation technique. Data are reported for the following reactions: 112Sn(n, 2n)111Sn, 118Sn(n, 2n)117Sn and 124Sn(n, 2n)123mSn. The neutron fluences were determined using the monitor reaction 93Nb(n, 2n)92mNb or 27Al(n, α)24Na. The results of present work were compared with data published previously.

Based on customer-oriented e-commerce flow, this paper analyses the knowledge of e-commerce flow and builds e-commerce domain ontology and sub-ontology. Based on this analysis, this paper builds reusable model of e-commerce domain ontology by using ontology construction standard technology. This reusable model can reveal the knowledge and the relationship between knowledge of the e-commerce flow deeply to meet the actual needs of designing e-commerce domain ontology.

China began to research the tertiary oil recovery process from the 1980s. This technology is very mature in the current, but the economic benefits for the EOR project evaluation studies are relatively less and simple, moreover, the evaluation method is single, almost all enterprises have chosen to use net present value method. But net present value method ignores the flexibility which is managed by the decision-makers under uncertainty, not suitable for oil field development investment project evaluation. Real option valuation and strategic decision-making are an important way of thinking, often used in the evaluation of oil exploration, but for oil and gas production, dynamic process of evaluation studies are rarely involved. As the EOR project has the option characteristics, this article will introduce the idea of real options to the EOR project and try to establish the differential equation model of the EOR project evaluation. Differential equations are used for tertiary oil recovery project to analyze the option value.

In this paper, the concept of invisible conveyance ability for logistics enterprise is put forward. According to the characters of road conveyance for logistics enterprise, we establish the index system of road conveyance capacity. After delimiting and analyzing the related indexes, we build a model based on the BP neural network from three stages, and make an empirical analysis, finally discuss the direction and meaning of applications in modern logistics.

The programmable AC power source is the important signal source in the power source measurement filed. It is necessary to ensure precision of the voltage signals that the programmable AC power source outputs. For the sake of confirming precision of the voltage signals, there are lots of testing items for the programmable AC power source. These testing items result in enormous workload. In order to improve testing efficiency for the programmable AC power source, the control and testing system is designed based on LabVIEW. The control and testing system can realize communication between the computer and the programmable AC power source via GPIB, assign the voltage parameters, control the programmable AC power source, and moreover, the system can acquire, extract and process the testing data and automatically create testing report. This paper introduces the control and test system and its realization method. It is known from the actual testing that the testing efficiency and the testing precision both are enhanced because of the use of this system. The technology and method adopted in the control and testing system are practical and worthy of using abroad.

The subspeciesNostoc commune var.flagelliforme andN. commune var.commune are found in China (Ningxia Province, Inner Mongolia) as two morphologically different ecotypes of the desiccation-independent cyanobacteriumN. commune. The first ecotype, but not the second, colonizes arid areas. Various biochemical parameters and water dependence of photosynthesis and nitrogen fixation were compared for both ecotypes. Different patterns of water stress proteins were found in the two ecotypes. Repeated desiccation resulted in an enhanced desiccation independence for photosynthesis and, in the case of the ecotypecommune, for nitrogen fixation. The different response of nitrogenase of both ecotypes towards repeated cycles of rewetting and desiccation under conditions simulating the natural environment is discussed in terms of the energy balance of the colonies that are adapted to different environmental conditions.

To explore the pharmacologic effects of Chinese medicine Bushen Huayu Jiedu Compound Recipe (BSHYJDR) in drug-resistance cells of lung cancer.Human lung adenocarcinoma A549/DDP cell strain was selected, serum pharmacology and flow cytometer (FCM) method were adopted, S180 tumor-bearing mice and normal mice were given, through gastrogavage, different doses of a decocted concentration of BSHYJDR. Serum from the abdominal aorta was taken to observe the effect of drug-serum on cisplatin (DDP) concentration, free Ca2+ concentration and the expression of lung drug-resistance protein LRP-56 in A549/DDP cells.Compared with the drug-resistance group, the intracellular DDP concentration in the group taking a high dose and the normal group of Chinese medicine showed significant difference (P0.05), while no significant difference was found in the low-dose group (P0.05). Compared with the drug-resistance group, the Ca2+ concentration in cells and the expression of LRP in lung cancer drug-resistance cells A549/DDP of the high-dose group, the low-dose group and the normal group of Chinese medicine were significantly different (all P0.01), the LRP expression of the normal group was obviously higher than that of the drug-resistance group (P0.05).It was indicated that serum containing Chinese medicine BSHYJDR in the tumor-bearing mice and the normal mice had certainly different, tumor-bearing mice serum containing could improve drug concentration in lung cancer drug-resistance cells, prevent the inflow and release of Ca2+, and inhibit the expression of the drug-resistance gene in the lung cancer drug-resistance cells, which might be the mechanism of BSHYJDR in enhancing the efficacy in reversing and inhibiting tumor.

Chloroplasts as photosynthetic apparatus, usually exist in leaves, but it has been found that a few young fruits also contain chloroplasts, such as apple[1], orange[2], avocado[3], grape[4], pod wall of pea[5], etc. The size of the chloroplasts is smaller than those in leaves, with lamella structrue, large starch granules and few thylakoids per granum[6]. These chloroplasts are gradually disintegrated with the fruit development. And they can be hardly found when the fruits are in full maturity[7]. From young to ripen, the pulp tissues of kiwifruit always contain chlorophyll[8]. The chloroplasts having primary structure had been found in pericarp of the mature kiwifruit by Possingham, etc[9]. The chloroplasts of kiwifruit exist in a microenvironment where there are thick pulp, light scarcity and low pH value. It has not been found any reports about the structure and photosynthetic activity of the kiwifruit chloroplasts. In this work the structure of kiwifruit chloroplasts which are in pericarp, mesocarp and core have been viewed by transmission electron microscope, and compared with kiwifruit leaves.

The formation of target wave in the network of Hodgkin-Huxley neuron with four variables is investigated by inputing a distribuled current. A stimulus current (I1) is input in to a local square area, and another stimulus current (I2) is input into the nodes of the network thus the distributed current is depicted. The development of target wave is measured by changing the coupling intensity, the size (number of the controlled neurons) of the local area into which current I1 is input, the gradient current (I =I1-I2). It is found that higher gradient current (I) is necessary to induce target wave when local area into which current I1 is input is smaller in size and the coupling intensity is higher in value. Finally, the potential mechanisms of the stimulus current and target wave formation are discussed in brief. Eextensive numerical results confirm that the developed target wave is robust to a certain channel noise.