10000KN封头冲压液压机的技术改造

针对１００００ＫＮ封头冲压液压机存在的问题，论述了液压机本体部分的改造技术，改造后的设备性能及特点等，对类似设备的技术改造具有参考价值。     

Ultrasonic motor-actuated direct drive positioning servo control system using fuzzy-reasoning controller

This paper describes a traveling-wave ultrasonic motor (USM)-actuated positioning servo driver, suitable for direct-drive motion systems, which incorporates a fuzzy-reasoning software controller with speed and position-variable feedback schemes. The experimental results of this USM position servo driver operating at two-phase high-frequency resonant inverter are illustrated and evaluated using a one-axis servo motion drive system. The results show that the new system using a compact USM that incorporates a microprocessor-based two-input and one-output fuzzy-reasoning controller is cost effective and suitable for special purposes in the industrial, medical, automotive, space and consumer fields.     

Adenovirus-mediated transduction with human glial cell line-derived neurotrophic factor gene prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopamine depletion in striatum of mouse brain

OBJECTIVE: This study assesses intravascular density produced by ionic and nonionic contrast material and its effect on visualization of stenoses by CT angiography. MATERIALS AND METHODS: CT angiography was performed using a 32-vessel phantom to study grades of luminal stenoses (0-100%), three lengths of stenoses (1, 3, and 5 mm), and two angles of inclination into the stenoses (45 degrees and 75 degrees). Scans were obtained with a slice thickness of 2 mm, a slice interval of 1.5 mm, a pitch of 1.0, a voltage of 120 kV, and a current of both 100 and 200 mA. Vessels were oriented parallel to the z-axis, and opacified with ionic and nonionic contrast material that had densities of 100, 150, 200, 250, 300, and 350 H. Cross-sectional luminal diameters were measured in and out of the stenoses. Edge definition and halo artifact for each vessel were graded by an investigator who was unaware of the contrast material density used. RESULTS: A contrast density of 150 H as revealed by CT angiography yielded the most accurate stenosis measurements with ionic contrast material. For nonionic contrast material, attenuation values of 150 and 200 H produced the best results on CT angiography. A density of 100 H or greater than 250 H significantly increased the error of vessel measurement (p = .001) for both types of contrast material. For the two current levels tested (100 and 200 mA), no statistical difference was found. CONCLUSION: The accuracy of CT angiography in measuring carotid stenosis depends on the luminal attenuation value. An optimum contrast density is 150 H for ionic contrast material; for nonionic contrast material, 150-200 H (at the window and level settings of 300 H and 40 H).     

Robust speed control system considering vibration suppressioncaused by angular transmission error of planetary gear

This paper proposes a new robust speed control to suppress vibration caused by angular transmission error of planetary gears. For this purpose, this paper first constructs a new numerical simulation model of angular transmission error of planetary gear, which is confirmed by experimental data from a robot arm. Next, in order to suppress the vibration caused by angular transmission error, we propose a robust speed control system based on disturbance observer and coprime factorization. Numerical simulation results show that the proposed system regulates the angular speed of motor satisfactorily, and it suppresses the vibration caused by angular transmission error     

NMR Study on the Electronic Structure of the Vortex State in HTSC

By using spatially-resolved NMR method, we observed nuclear spin-lattice relaxation rate (1/T ₁) of the vortex state to probe antiferromagnetic correlations at the vortex core. We found that the temperature dependence of 1/T ₁ shows a peak, which results from a local antiferromagnetic ordering of Cu spins in the vortex core.     

Stage-Specific Characterization of Physiological Response to Heat Stress in the Wheat Cultivar Norin 61

Bread wheat (Triticum aestivum) is less adaptable to high temperatures than other major cereals. Previous studies of the effects of high temperature on wheat focused on the reproductive stage. There are few reports on yield after high temperatures at other growth stages. Understanding growth-stage-specific responses to heat stress will contribute to the development of tolerant lines suited to high temperatures at various stages. We exposed wheat cultivar “Norin 61” to high temperature at three growth stages: seedling–tillering (GS1), tillering–flowering (GS2), and flowering–maturity (GS3). We compared each condition based on agronomical traits, seed maturity, and photosynthesis results. Heat at GS2 reduced plant height and number of grains, and heat at GS3 reduced the grain formation period and grain weight. However, heat at GS1 reduced senescence and prolonged grain formation, increasing grain weight without reducing yield. These data provide fundamental insights into the biochemical and molecular adaptations of bread wheat to high-temperature stresses and have implications for the development of wheat lines that can respond to high temperatures at various times of the year.     

Zinc adsorption effects on arsenite oxidation kinetics at the birnessite-water interface

Arsenite is more toxic and mobile than As(V) in soil and sediment environments, and thus it is advantageous to explore factors that enhance oxidation of As(III) to As(V). Previous studies showed that manganese oxides, such as birnessite (delta-MnO2), directly oxidized As(III). However, these studies did not explore the role that cation adsorption has on As(III) oxidation. Accordingly, the effects of adsorbed and nonadsorbed Zn on arsenite (As(III)) oxidation kinetics at the birnessite-water interface were investigated using batch adsorption experiments (0.1 g L(-1); pH 4.5 and 6.0; I= 0.01 M NaCl). Divalent Zn adsorption on synthetic delta-MnO2 in the absence of As(II) increased with increasing pH and caused positive shifts in electrophoretic mobility values at pH 4-6, indirectly suggesting inner-sphere Zn adsorption mechanisms. Arsenite was readily oxidized on birnessite in the absence of Zn. The initial As(III) oxidation rate constant decreased with increasing pH from 4.5 to 6.0 and initial As(III) concentrations from 100 to 300 microM. Similar pH and initial As(III) concentration effects were observed in systems when Zn was present (i.e., presorbed Zn prior to As(III) addition and simultaneously added Zn-As(III) systems), but As(III) oxidation reactions were suppressed compared to the respective control systems. The suppression was more pronounced when Zn was presorbed on the delta-MnO2 surfaces as opposed to added simultaneously with As(III). This study provides further understanding of As(III) oxidation reactions on manganese oxide surfaces under environmentally applicable conditions where metals compete for reactive sites.     

Arsenic speciation and reactivity in poultry litter

Recent U.S. government action to lower the maximum concentration levels (MCL) of total arsenic (As) (10 ppb) in drinking water has raised serious concerns about the agricultural use of As-containing biosolids such as poultry litter (PL). In this study, solid-state chemical speciation, desorbability, and total levels of As in PL and long-term amended soils were investigated using novel synchrotron-based probing techniques (microfocused (micro) synchrotron X-ray fluorescence (SXRF) and micro-X-ray absorption near-edge structure (XANES) spectroscopies) coupled with chemical digestion and batch experiments. The total As levels in the PL were as high as approximately 50 mg kg(-1), and As(II/III and V) was always concentrated in abundant needle-shaped microscopic particles (approximately 20 microm x 850 microm) associated with Ca, Cu, and Fe and to a lesser extent with S, Cl, and Zn. Post-edge XANES features of litter particles are dissimilar to those of the organo-As(V) compound in poultry feed (i.e., roxarsone), suggesting possible degradation/transformation of roxarsone in the litter and/or in poultry digestive tracts. The extent of As desorption from the litter increased with increasing time and pH from 4.5 to 7, but at most 15% of the total As was released after 5 d at pH 7, indicating the presence of insoluble phases and/or strongly retained soluble compounds. No significant As accumulation (< 15 mg kg(-1)) was found in long-term PL-amended agricultural surface soils. This suggests that As in the PL may have undergone surface and subsurface transport processes. Our research results raise concerns about long-term PL amendment effects on As contamination in surrounding soil-water environments.     

Calibration of solar simulator for evaluation of dye-sensitized solar cells

The photo-to-electricity energy conversion efficiencies of ruthenium-dye-sensitized solar cells (DSC) are measured under a solar simulator. The error in conversion efficiencies was compared under a variety of spectral conditions. Measurements of the conversion efficiencies of DSC between a solar simulator and outdoor sunlight result in about 10% error. This error was seen when the spectral intensity of a xenon-lamp solar simulator (imitating an air mass (AM) 1.5 spectrum) was adjusted by the short-circuit photocurrent I_Si of a crystalline silicon (c-Si) standard cell. In order to adjust the energetic intensity of AM 1.5 for DSC that has a spectrum response only in the visible region light, the c-Si reference cell is modified with a glass UV filter (KG-5, Schott) and the solar simulator was adjusted by I_{IR-cut Si}. The energetic spectrum of the solar simulator has a good accuracy over the wavelength range 300–750 nm, giving the conversion efficiency of DSC an accuracy of about 2%. The dependency of the ratio of I_Si to I_{IR-cut Si} on natural sun power is discussed in view of scattering of the visible light under changing natural sun light.