回族作家李进祥小说《换水》的空间叙事研究

回族作家李进祥的小说《换水》通过对城市与乡村两个空间的书写,反映出城市与乡村不仅具有地理意义上或者是社会形态上的区别,还具有文化心理和意识形态的差异。小说用传统的"换水"仪式来象征生存空间的转移和变迁,同时呈现出生活在两种不同文化之间的底层人物的生存状态。"换水"仪式的书写寄托着李进祥对民族传统文化的情感认同,也是其自我回归的一种诉说。由此,本文主要分析李进祥小说《换水》的空间叙事。

论回族作家李进祥小说《换水》的精神回归

在"全球化"语境中,回族作家李进祥通过对城市空间的"逃离"与乡村空间的"返乡"这一行为的疼痛书写来实现把自己从都市"时空结构"中解脱出来,返回到乡村"时空结构"中,表征着对城市空间内金钱至上、冷漠无情的生存状态的抗争与疏远。李进祥的大部分作品都是书写社会底层人物在都市漩涡中的生存困境与追寻,在《换水》中不断地重构乡村生活的缓慢与宁静,重塑民族文化的"时空结构",最终实现自我的"文化返乡"。

Effects of Different Water Stresses on Eco-physiological Characteristics of Hippophae rhamnoides Seedlings

In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.

A 71mW 8b 125MSample/s A/D Converter

A 1.8V 8b 125Msample/s pipelined A/D converter is presented.Power efficiency is optimized by size scaling down scheme using low power single stage cascode amplifier with a gain boosted structure.Global clock tree and local generators are employed to avoid loss and overlap of clock period.The ADC achieves a signal-to-noise-and-distortion ratio (SNDR) of 49.5dB(7.9ENOB) for an input of 62MHz at full speed of 125MHz,consuming only 71mW.It is implemented in 0.18μm CMOS technology with a core area of 0.45mm 2.

Contourlet watermarking algorithm based on Arnold scrambling and singular value decomposition

A new digital watermarking algorithm based on the contourlet transform is proposed to improve the robustness and anti-attack performances of digital watermarking. The algorithm uses the Arnold scrambling technique and the singular value decomposition （SVD） scheme. The Arnold scrambling technique is used to preprocess the watermark, and the SVD scheme is used to find the best suitable hiding points. After the contourlet transform of the carrier image, intermediate frequency sub-bands are decomposed to obtain the singularity values. Then the watermark bits scrambled in the Arnold rules are dispersedly embedded into the selected SVD points. Finally, the inverse contourlet transform is applied to obtain the carrier image with the watermark. In the extraction part, the watermark can be extracted by the semi-blind watermark extracting algorithm. Simulation results show that the proposed algorithm has better hiding and robustness performances than the traditional contourlet watermarking algorithm and the contourlet watermarking algorithm with SVD. Meanwhile, it has good robustness performances when the embedded watermark is attacked by Gaussian noise, salt- and-pepper noise, multiplicative noise, image scaling and image cutting attacks, etc. while security is ensured.

Reconfigurable implementation of AES algorithm IP core based on pipeline structure

In order to improve the data throughput of the advanced encryption standard （AES） IP core while reducing the hardware resource consumption and finally achieving a tradeoff between speed and area, a mixed pipeline architecture and reconfigurable technology for the design and implementation of the AES IP core is proposed. The encryption and decryption processes of the AES algorithm are achieved in the same process within the mixed pipeline structure. According to the finite field characterizations, the Sbox in the AES algorithm is optimized. ShiftRow and MixColumn, which are the main components in AES round transformation, are optimized with the reconfigurable technology. The design is implemented on the Xilinx Virtex2p xc2vp20-7 field programmable gate array （FPGA） device. It can achieve a data throughput above 2.58 Gbit/s, and it only requires 3 233 slices. Compared with other related designs of AES IP cores on the same device, the proposed design can achieve a tradeoff between speed and area, and obtain satisfactory results in both data throughput and hardware resource consumption.

Effects of Nitrogen Fertilizer Regulation with Straw-return on Wheat Yield and Different Forms of Potassium in the Soil

In order to study the effects of nitrogen fertilizer application methods and nitrogen fertilizer regulation with straw-return on wheat yield and potassium forms in the soil, field experiment was arranged in Pinyuan County, and the effects of the regulation of different ratios of basal to topdressed nitrogen on the yield of wheat and the contents of different forms of potassium in the soil were studied. The re- sults indicated that in the condition of straw-return, the yield of wheat was the high- est after the treatments of the ratios of basal to topdressed nitrogen of 7：3 and 6：4. As to the contents of different forms of potassium, the contents of water-soluble potassium, exchangeable potassium and total potassium treated by the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the highest, and the differences of non-exchangeable potassium among all treatments were not significant. Under the experiment condition, the ratios of basal to topdressed nitrogen of 7：3 and 6：4 were the best treatments, they can increase the wheat yield and the contents of available potassium and total potassium in the soil.

Mapping of QTLs Related to Grain Weight Using Chromosome Single Segment Substitution Lines in Rice

Grain weight, one of the major factors determining rice yield, is a typical quantitative trait control ed by multiple genes. With Guangluai 4 as recipient and Nipponbare as donor, a population of 119 chromosome single segment substitution lines had been developed. Correlation analysis between grain weight and grain shape by SPSS revealed that 1 000-grain weight shared extremely significant posi-tive correlation with grain length and length-width ratio, but no significant correlation with grain width and thickness. The QTL analysis of grain weight was carried out using one-way analysis of variance and Dunnett＇s test. Nineteen stable QTLs re-sponsible for grain weight were identified over two years. Al 19 QTLs were identi-fied on al chromosomes except for chromosome 10 and 12 at a significance level of P≤0.001. Among them, 10 QTLs had a positive effect and were derived from the Nipponbare al ele, the additive effect of these QTLs ranged from 0.49 to 2.74 g, and the contributions of the additive effects ranged from 2.00% to 11.05%. Another 9 QTLs had a negative effect and were al derived from Guangluai 4 al ele, the ad-ditive effect of these QTLs ranged from 0.60 to 2.35 g, and the contributions of the additive effects ranged from 2.40% to 9.84%. The results provide a basis for the fine mapping and gene cloning of novel locus associated with rice grain weight.

Fourier Transform Infrared Spectral Difference of Leaf Tips in Rice Related to Nitrogen Fertilizer Rates

Fourier transform infrared spectroscopy (FTIR) was used to detect the spectral difference among leaf tips from rice ( Oryza sativa L.) plants with different nitrogen fertilizer rates. The proposed spectral index, ( A 3400 - A 1653 )/( A 3400 + A 1653 ) ( A denotes absorption value at certain frequency (cm -1 )), was found to decline with the increase of nitrogen fertilizer rates and the results suggested that FTIR may be useful to diagnose nitrogen status in crops.

Effect of NH_4^+ exchange on CuY catalyst for oxidative carbonylation of methanol

NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY cata‐lysts by a high temperature anhydrous interaction between the support and copper （II） acety‐lacetonate Cu（acac）2. The catalysts were used for the oxidative carbonylation of methanol to dime‐thyl carbonate （DMC） at atmospheric pressure. The textural and acidic properties of NaNH4Y zeolite and the CuY catalysts were investigated by X‐ray diffraction, scanning electron microscopy, N2 ad‐sorption‐desorption, temperature programmed reduction of H2, X‐ray photoelectron spectroscopy and temperature programmed desorption of NH3. With increasing NH4NO3 concentration, the NH4＋exchange degree increased while the crystallinity of the zeolite remained intact. Crystalline CuO was formed when the NH4＋exchange degree of NaNH4Y was low, and the corresponding CuY catalyst showed low catalytic activity. With increasing of the NH4＋exchange degree of NaNH4Y, the content of surface bound Cu＋active centers increased and the catalytic activity of the corresponding CuY catalyst also increased. The surface bound Cu＋content reached its maximum when the NH4＋ex‐change degree of NaNH4Y reached towards saturation. The CuY exhibited optimal catalytic activity with 267.3 mg/（g·h） space time yield of DMC, 6.9%conversion of methanol, 68.5%selectivity of DMC.

One-dimensional consolidation of visco-elastic aquitard due to withdrawal of deep-groundwater

One-dimensional consolidation of visco-elastic aquitard due to withdrawal of deep-groundwater was studied.Merchant model was used to simulate visco-elastic characteristic of aquitard.General solutions of the governing equation were obtained by applying Laplace transform with respect to time,and then the pore-pressure,strain and deformation of the aquitard could be calculated by Laplace inversion.A case was analyzed to validate the correctness of the present method.Finally,some consolidation properties of the problem were analyzed.Comparison of the average degree of consolidation defined by pore pressure with that defined by settlement shows that they are different and the maximum difference is 22.8%.The influences of parameters of Merchant model and the rate of the water level on the consolidation are great.The smaller the viscosity coefficient is,the later the rate of consolidation decreases.The rate of consolidation is decreased with the decrease of the rate of the water level fall.Therefore,the lagged effect of land subsidence should be considered in the actual project.

An Audio Zero-Watermark Scheme Based on Energy Comparing

Zero-watermark technique,embedding watermark without modifying carriers,has been broadly applied for copyright protection of images.However,there is little research on audio zerowatermark.This paper proposes an audio zero-watermark scheme based on energy relationship between adjacent audio sections.Taking use of discrete wavelet transformation(DWT),it gets power approximations,or energies,of audio segments.Then,it extracts the audio profile,i.e.the zero-watermark,according to the relative size of energies of consecutive fragments.The experimental results demonstrate that the proposed scheme is robust against general malicious attacks including noise addition,resampling,low-pass filtering,etc.,and this approach effectively solves the contradiction between inaudibility and robustness.

Water exchange through the Kerama Gap estimated with a 25-year Pacific HYbrid Coordinate Ocean Model

Variations in water exchange through the Kerama Gap （between Okinawa Island and Miyakojima Island） from 1979 to 2003 were estimated with the 0.08° Pacific HYbrid Coordinate Ocean Model （HYCOM）. The model results show that the mean transport through the Kerama Gap （KGT） from the Pacific Ocean to the East China Sea （ECS） was 2.1 Sv, which agrees well with the observed mean KGT （2.0 Sv） for 2009- 2010. Over the time period examined, the monthly KGT varied from -10.9 Sv to 15.8 Sv and had a standard deviation of ＋5.0 Sv. The water mainly enters the ECS via the subsurface layer （300-500 m） along the northeastern slope of the Kerama Gap and mainly flows out of the ECS into the southwest of the Kerama Gap. The seasonal and interannual variations of the KGT and the Kuroshio upstream transport were negatively correlated. The Kuroshio upstream transport was largest in summer and smallest in auamm while the KGT was smallest in summer （1.02 Sv） and largest in spring （2.94 Sv） and autumn （2.44 Sv）. The seasonal and interarmual variations in the Kuroshio downstream （across the PN-line） transport differed significantly from the Kuroshio upstream transport but corresponded well with the KGT and the sum of the transport through the Kerama Gap and the Kuroshio upstream, which indicates that information about variation in the KGT is important for determining variation in the Kuroshio transport along the PN-line.

Study on Hydraulic System Efficiency of Heaving-Buoy Wave Energy Converter

The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy WEC.We derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy accumulator.The model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic resistance.We also studied the relationship between the efficiency and the initial conditions.Finally,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.

Sediment Movement in Periodic Alternating Current

The present paper summarizes the results of previous studies, including the structure and principle of the rotary ring flume for researching the fine sediment movement, the mechanism of the flume, method of eliminating the influence of the centrifugal force and sediment movement experiments with periodic alternating current. Also included are the experiment-based relationship among sediment concentration, bed shear stress and silt carrying capacity, a proposed erosion-deposition function and bed erosion-deposition calculation together with the results of verification.

Influence of Reclamation Works on the Marine Environment in a Semi-Enclosed Bay

The flow and seawater exchange rates have been predicted using a two-dimensional numerical model and a Lagrangian method for a semi-enclosed shallow bay where reclaiming and dredging works are scheduled. The wind effect on the flow and material transport has been emphasized, and a thirty-year mean value of wind has been considered in the numerical simulation. As a whole, even after the reclaiming and dredging are conducted, the flow pattern looks similar to the original state. However, velocity variations up to 20% to 100% appear in the vicinity of the construction area. In the case of summcr wind forcing, the seawater exchange rate increases from 71.6% to 82.9% after the reclaiming and dredging, as indicated by a particle-tracking method. On the contrary, in the case of winter wind forcing, thc seawater cxchange rate appears to be 97.2% under natural conditions but decrcases slightly to 93.2% aftcr the rcclaiming and dredging. Thus, the wind forcing plays an important role in controlling the seawater exchangc rates. The seawater cxchange rate is further improved by 15% if the dredging is simultaneously carried out with the reclaiming. This suggests that the dredging can be an effective means to mitigate the variation of flow.

Simulation and Design Optimization of Ammonia Synthesis Converter

One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability(RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.

Study on inhomogeneous cooling behavior of extruded profile with unequal and large thicknesses during quenching using thermo-mechanical coupling model

The interfacial heat transfer coefficient between hot profile surface and cooling water was determined by using inverse heat conduction model combined with end quenching experiment. Then, a Deform-3 D thermo-mechanical coupling model for simulating the on-line water quenching of extruded profile with unequal and large thicknesses was developed. The temperature field, residual stress field and distortion of profile during quenching were investigated systematically. The results show that heat transfer coefficient increases as water flow rate increases. The peak heat transfer coefficient with higher water flow rates appears at lower interface temperatures. The temperature distribution across the cross-section of profile during quenching is severe nonuniform and the maximum temperature difference is 300 ℃ at quenching time of 3.49 s. The temperature difference through the thickness of different parts of profile first increases sharply to a maximum value, and then gradually decreases. The temperature gradient increases obviously with the increase of thickness of parts. After quenching, there exist large residual stresses on the inner side of joints of profile and the two ends of part with thickness of 10 mm. The profile presents a twisting-type distortion across the cross-section under non-uniform cooling and the maximum twisting angle during quenching is 2.78°.

Benthic nutrient recycling in shallow coastal waters of the Bohai Sea

Sediment-water fluxes of N and P species in the Bohai Sea were investigated in Septem-ber-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples with bottom seawater bubbled with air or nitrogen. -2NO,+4NH, dissolved organic nitrogen (DON) and phosphorus (DOP), total dissolved nitrogen (TDN) and phosphorus (TDP), and -34PO showed a net exchange flux from seawater to sediment, while -3NO, dissolved inorganic nitrogen (DIN) and -23SiO were released from sediment to seawater in the Bohai Sea. Sediment-water nutrient exchange increases DIN and reduces the phosphorus load in the Bohai Sea. The release of silicate from sediment to overlying seawater reduces potential silicate limitation of primary production resulted from decrease of riverine discharge. The exchange flux of nutrients showed no obvious seasonal variation. The present study showed that the concentrations and composition of nutrients in the water column were affected by suspended sediment, and that not all the exchangeable phosphate in sediment could be released via sediment resuspension.