滇中地区水稻光温生产潜力的动态模拟

农业生产潜力与经济发展密切相关 ,而作物的光温生产潜力是影响农业生产潜力的重要因素。本文针对滇中地区区域地理特征 ,结合中日合系 2 6号水稻的田间实验观测资料 ,对滇中水稻光温生产潜力进行了动态模拟 ,将模拟结果与实验数据进行了对比 ,并作出了初步分析和讨论。

安捷光电:光纤传感 保障安全 访深圳市安捷工业光电有限公司总工程师陈志标博士

光纤传感技术是伴随光纤通信技术而迅速发展起来的新型传感技术，光纤传感以光波为载体，光纤为介质，感知和传输外界被测量信号。光纤本身具有不带电、体积小、质量轻、易弯曲、抗电磁干扰和抗辐射的特性，特别适用于易燃、易爆、空间受严格限制和强电磁干扰等恶劣环境，解决了许多行业多年来一直存在的技术难题，具有很大的市场需求，发展空间相当广阔。

沟灌条件下土壤水热传输与转换研究进展

沟灌地表的不均匀结构使土壤水热运动具有空间性,地表水汽交换与光温条件随之改变。该文概述了近年来国内外沟灌土壤的水热传输与转换的研究进展,主要包括地-气界面的水汽交换、沟垄表面的光温分布和沟灌土壤的水热传输。深入阐明沟灌土壤的水热传输机制,是沟灌条件下土壤水热资源高效利用的基础。

Optical-fiber distributed temperature sensor:design and realization

Through analyzing theoretically the temperature effect of the optical-fiber Raman backscattering,a distributed temperature sensor is designed based on the single-mode fiber. Demodulation methods of temperature transduction are compared,and then the demodulation method using the ratio of the anti-Stokes and the Stokes Raman backscattering intensity is adopted. Both the hardware composition and the software realization of the system are introduced in detail. The experiment shows that the distinguishing ability of the temperature and that of the space are 1℃ and 2m,respectively,and that the system response time is about 180 s with a sensing range of 5km and with a temperature measurement range of 0-100℃.

Development of 2D Temperature and Concentration Measurement Method Using Tunable Diode Laser Absorption Spectroscopy

Exhaust gas temperature is an important factor in NOx, THC and PM emissions of engines. Especially 2D temperature and concentration distribution plays an important role for the engine efficiency. A thermocouple is intrinsically a point temperature measurement method and noncontact 2D temperature distribution cannot be attained by thermocouples. Recently, as a measurement technique with high sensitivity and high response, laser diagnostics has been developed and applied to the actual engine combustions. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. In this study, the theoretical and experimental research has been conducted in order to develop the noncontact and fast response 2D temperature and concentration distribution measurement method. The method is based on a Computed Tomography （CT） method using absorption spectra of water vapor at 1388 nm. It has been demonstrated that the method has been successfully applied to engine exhausts to measure 2D temperature distributions.

Flame radiant image numeralization for pulverized coal combustion in BF raceway

In order to establish correlativity between pulverized coal combustion in a blast furnace raceway and its radiant image, we investigated the relationships between two dimensional radiant images and three dimensional radiant energy in a blast furnace raceway, focusing on the correlativity of the numerical simulation of combustion processes with the connection of radiant images information and space temperature distribution. We calculated the uneven radiate characteristic parameterby taking radiant images as a kind of radiative boundary for numerical simulation of combustion processes, and put fonward a method to examine three-dimensional temperatures distribution in blast furnace raceway by radiant image processing. The numeral temperature fields matching the real combustion can be got by the numeric image processing technique.

Thermal analysis of an innovative flat heat pipe radiator

An innovative flat heat pipe radiator was put forward, and it has the features of high efficiency of heat dissipation, compact construction, low thermal resistance, light weight, low cost, and anti-dust-deposition. The thermal analysis of the flat heat pipe radiator for cooling high-power light emitting diode （LED） array was conducted. The thermal characteristics of the flat heat pipe radiator under the different heat loads and incline angles were investigated experimentally in natural convection. An electro-thermal conversion method was used to measure the junction temperature of the LED chips. It is found that the integral temperature distribution of the flat heat pipe radiator is reasonable and uniform. The total thermal resistance of the flat heat pipe radiator varies in the range of 0.38-0.45 K/W. The junction temperatures of LED chips with the flat heat pipe radiator and with the aluminum board at the same forward current of 0.35 A are 52.5 and 75.2 ℃, respectively.

Transient Thermal Analysis of Ridge Waveguide InAsP/InGaAsP MQW Lasers Operating in Pulse Driving Conditions

The transient thermal characteristics of the ridge waveguide InAsP/InGaAsP MQW lasers, especially in various pulse driving conditions,have been simulated by using FEM. The temperature at the active core of the laser versus the time has been calculated as well as pulse width dependence of the apparent thermal resistance.The results show that the thermal characteristics of the lasers are related to both the thermal conductivity and the specific heat of the materials.

Short-Term Responses of Nitrous Oxide Emissions and Concentration Profiles to Fertilization and Irrigation in Greenhouse Vegetable Cultivation

In vegetable cultivation, the majority of N2O emissions occur after fertilization; it is therefore important to understand any factors contributing to this process. An experiment was conducted to investigate short-term N2O dynamics following topdressing in a greenhouse vegetable field in South China. During two topdressing processes, three different urea-N treatments with irrigation were conducted in May and June in a tomato （Lycopersicum esculentum） cultivation. The N2O fluxes, soil concentration profiles and soil environments at the 0-60 cm depths at 10 cm intervals were measured both immediately prior to and 5 days after topdressing. The N2O fluxes before topdressing ranged from 6.7=1=2.1 to 55.0-4-28.8 μg N m-2 h-1; even higher numbers were recorded in highly fertilized plots. The NO3-N accumulation in the soil caused by vegetable cultivation during the 5 years prior to the start of the experiment, resulted in high background N2O fluxes. One day after topdressing （1 DAT） in May and June, N2O fluxes increased, which coincided with sharp increases in soil N2O concentrations at depths of 2.5 and 15 cm and in NOa-N and NH4＋-N contents at depths of 0-20 cm. From 1 to 5 DAT, fluctuations in the N2O fluxes did not harmonize with the N2O concentrations at a depth of 2.5 cm, which was attributed to different gas diffusion rates at depths of 0-10cm. These results suggested that surface soil N and environmental conditions were crucial for determining the short-term N2O ebullitions during topdressing in greenhouse vegetable cultivation.

Distributed Discrimination of Strain and Temperature Based on Brillouin Dynamic Grating in an Optical Fiber

This paper reviews distributed discrimination of strain and temperature by use of an optical fiber based on fiber optic nerve systems. The preliminary method based on multiple resonance peaks of the Brillouin gain spectrum in a specially-designed fiber is firstly introduced. The complete discrimination of strain and temperature based on the Brillouin dynamic grating in a polarization maintaining fiber is extensively presented. The basic principle and two experimental schemes of distributed discrimination based on fiber optic nerve systems are demonstrated. The performance of the high discriminative accuracy （0.1 ~C-0.3 ~C and 5 kte-12~te） and high spatial resolution （-10 cm） with the effective measurement points of about 50 for a standard system configuration or about 1000 for a modified one will be highly expected in real industry applications.

Study of Optical Fibers Strain-Temperature Sensitivities Using Hybrid Brillouin-Rayleigh System

In this paper, the most recent progress as well as challenges of distributed optical fiber sensing （DOFS） in industrial applications is discussed. Compared to the vast market of sensors used to measure strain or temperature, the success of distributed optical fiber sensing （DOFS） at the industrial level is very limited, at best. One of the reasons for this lack of the wider acceptance is the mismatch between the commercially available systems and actual industrial requirements, especially for the spatial resolution and precision. These requirements are organized and clarified in the paper. It also describes the hybrid Brillouin-Rayleigh system, which exhibits capabilities surpassing those of strain gauges. The principles of the system are illustrated considering the fiber calibration methodology. Formulas required for determining strain, temperature, and hydro-pressure are derived and discussed. Finally, the examples of applications are presented.

A near-infrared methane detection system using a 1.654 μm wavelength-modulated diode laser

By adopting a distributed feedback laser(DFBL) centered at 1.654 μm, a near-infrared(NIR) methane(CH4) detection system based on tunable diode laser absorption spectroscopy(TDLAS) is experimentally demonstrated. A laser temperature control as well as wavelength modulation module is developed to control the laser's operation temperature. The laser's temperature fluctuation can be limited within the range of-0.02—0.02 °C, and the laser's emitting wavelength varies linearly with the temperature and injection current. An open reflective gas sensing probe is realized to double the absorption optical path length from 0.2 m to 0.4 m. Within the detection range of 0—0.01, gas detection experiments were conducted to derive the relation between harmonic amplitude and gas concentration. Based on the Allan deviation at an integral time of 1 s, the limit of detection(Lo D) is decided to be 2.952×10^(-5) with a path length of 0.4 m, indicating a minimum detectable column density of ~1.2×10^(-5) m. Compared with our previously reported NIR CH_4 detection system, this system exhibits some improvement in both optical and electrical structures, including the analogue temperature controller with less software consumption, simple and reliable open reflective sensing probe.