笋竹两用毛竹丰产培育试验初报

为研究深翻垦复、施肥模式对笋竹两用毛竹笋材产量的影响,经过连续3a对毛竹不同培育模式进行试验,并对相应的笋材产量比较分析,结果表明：笋竹两用毛竹的培育模式,应深翻垦复与施肥相结合,且施肥须长效肥与速效肥相结合,在6月毛竹行鞭时施长效肥,9~10月孕笋时施速效肥,这种培育模式最有利于毛竹笋材产量水平的提高。

Growth characteristics of multipurpose tree species, crop productivity and soil properties in agroforestry systems under subtropical humid climate in India

Multipurpose tree species （MPTs） were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2 m × 2 m （2500 stems·hm^-2） could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m^3·hm^-2 with mean annual increment （MAI） of 2.54×10^-2 m^3.treel.a^-1 in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3 m × 3 m （1111 stems.hm^2） produced appreciably high timber volume of 315 m^3.hm^-2 and 165 m^3.hm^-2 with MAI of 1.77×10^-2 m^3.tree^-1·a^-1 and 0.92×10.2 m^3.tree^-1.a^-1, respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m^3.hm^-2 with MAI of 1.47×10^-2 m^3.tree^-1.a^-1 followed by Samania saman （140 m^3.hm^-2）, Albizziaprocera （113 m^3·hm^-2） and Tectona grandis （79 m3.hm^-2） with MAI of 1.40, 1.13 and 0.78 × 10^-2 m^3 .tree^-1a^-1, respectively in 4 m × 4 m spacing （625 stems.hm^-2）. Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice （Oryza sativa - variety, AR-11）, groundnut （Arachis hypogaea - variety, JL-24） and sesamum （Sesamum indicum - variety, B-67） were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple （Ananas comosus - variety Queen）, turmeric （Curcuma longa -variety RCT -1） and cowpea （Vigna sinensis - variety Pusa Barsati） as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil （0-15 cm） moisture availability were noted in soils under MPTs.

Converting circular tubes into square cross-sectional parts using incremental forming process

Incremental forming process is recently developed to form tubular parts.The fabrication cost and accuracy could be optimized if the effects of process parameters and the optimum values are specified.The aim of this research is using incremental forming of copper tubes to convert a circular tube into a square cross-sectional part.An experimental setup,consisting of a spherical forming punch and a fixture for clamping the tube is designed.The forming punch movement is controlled by a CNC machine.Full factorial design of experiments is carried out in order to determine the effects of process parameters including linear velocity,radial feed,and axial feed of the tool on the thinning ratio and the maximum outer diameter of the square cross-sectional parts.Results show that the radial feed has the major influence on the thinning ratio,while the axial feed plays the major role for the final profile.Increase of radial feed results in higher thinning ratio,and decrease of axial feed results in better shape conformity.Linear velocity does not have a significant effect on thinning ratio.Regression models are also given for predicting the determined responses.

A Facile Route for Synthesis of LiFePO_4/C Cathode Material with Nano-sized Primary Particles

A facile and practical route was introduced to prepare LiFePO4/C cathode material with nano-sized primary particles and excellent electrochemical performance. LiH2PO4 was synthesized by using H3PO4 and LiOH as raw materials. Then, as-prepared LiH2PO4, reduced iron powder andα-D-glucose were ball-milled, dried and sin-tered to prepare LiFePO4/C. X-ray diffractometry was used to characterize LiH2PO4, ball-milled product and LiFePO4/C. Differential scanning calorimeter-thermo gravimetric analysis was applied to investigate possible reac-tions in sintering and find suitable temperature for LiFePO4 formation. Scanning electron microscopy was em-ployed for the morphology of LiFePO4/C. As-prepared LiH2PO4 is characterized to be in P21cn（33） space group, which reacts with reduced iron powder to form Li3PO4, Fe3（PO4）2 and H2 in ball-milling and sintering. The appro-priate temperature for LiFePO4/C synthesis is 541.3-976.7 ℃. LiFePO4/C prepared at 700 ℃ presents nano-sized primary particles forming aggregates. Charge-discharge examination indicates that as-prepared LiFePO4/C displays appreciable discharge capacities of 145 and 131 mA·h·g^-1 at 0.1 and 1 C respectively and excellent discharge ca-pacity retention.

A general strategy for high-throughput experimental screening of promising bulk thermoelectric materials

High-throughput(HTP)experiments play key roles in accelerating the discovery of advanced materials,but the HTP preparation and characterization,especially for bulk samples,are extremely difficult.In this work,we developed a novel and general strategy for HTP screening of high-performance bulk thermoelectric materials.The performed fullchain HTP experiments cover rapid synthesis of the bulk sample with quasi-continuous composition,microarea phase identification and structure analysis,and measurement of the spatial distribution of the sample composition,electrical and thermal transport properties.According to our experiments,bulk Bi_(2-x)Sb_(x)Te_(3)(x=1-2)and Bi_(2)Te_(3-x)Se_(x)(x=0-1.5)samples with quasi-continuous compositions have been rapidly fabricated by this HTP method.The target thermoelectric materials with the best Sb/Bi and Te/Se ratios are successfully screened out based on subsequent HTP characterization results,demonstrating that this HTP technique is effective in speeding up the exploration of novel high-performance thermoelectric materials.

Design, optimization, and measurement of closed-loop Hall effect current sensor

A kind of closed-loop Hall effect sensor is designed and fabricated by considering several factors such as iron core material, Hall device, as well as selected integrated circuit. Through studying the effect of the iron material and structures of current sensor, a kind of optimal Hall effect current sensor is found. The experimental results show that the presented closed-loop Hall effect current sensor achieves 1 mA/A sensitivity. And its lineafity and accuracy are 0.1% and 0.35% FS, respectively, at cur- rents ranging from 0 to 50 A.