Nondestructive measurement of thermal contact resistance for the power vertical double-diffused metal-oxide-semiconductor

To obtain thermal contact resistance（TCR） between the vertical double-diffused metal-oxide-semiconductor（VDMOS） and the heat sink, we derived the relationship between the total thermal resistance and the contact force imposed on the VDMOS. The total thermal resistance from the chip to the heat sink is measured under different contact forces, and the TCR can be extracted nondestructively from the derived relationship. Finally, the experimental results are compared with the simulation results.

Measurement of sugar content in Fuji apples by FT-NIR spectroscopy

To evaluate the potential of FT-NIR spectroscopy and the influence of the distance between the light source/detection probe and the fruit for measuring the sugar content (SC) of Fuji apples, diffuse reflectance spectra were measured in the spectral range from 12500 to 4000 cm^-1 at 0 mm, 2 mm, 4 mm and 6 mm distances. Four calibration models at four distances were established between diffused reflectance spectra and sugar content by partial least squares (PLS) analysis. The correlation coefficients (R) of calibrations ranged from 0.982 to 0.997 with SEC values from 0.138 to 0.453 and the SECV values from 0.74 to 1.58. The best model of original spectra at 0 mm distance yielded high correlation determination of 0.918, a SEC of 0.092, and a SEP of 0.773. The results showed that different light/detection probe-fruit distances influence the apple reflective spectra and SC predictions.

INVERSE COMPUTATION OF OPTICAL-ABSORPTION COEFFICIENT IN INHOMOGENEOUS MATERIAL WITH VARIED THERMAL CONDUCTIVITY

In this paper,for an inhomogeneous material in which the thermal conductivity varies as a function of depth,an efficient treatment is proposed to inversely calculate the depth distri- bution of optical- absorption coefficientby the surface temperature of the material.It is demon- strated that the results of inverse computation by that method are more similar to the experi- mental ones measured by some destructive method.Thus,the treatmentis more feasible to non- destructively estimate the distribution.

Online ultrasonic terminal for measuring pig backfat thickness

The measurement of pig backfat thickness(PBFT)has to stand up to challenges with the reliability,accuracy,and convenience.Acquiring PBFT timely and precisely from a finite distance is extremely necessary to improve the process of pig production and implement effective management.In an attempt to alleviate these problems,an online handheld terminal was designed with a new method based on ultrasonic technology for measuring PBFT during the process of pig breeding,which can overcome the difficulties encountered in other destructive means.The terminal comprised three main components:a main microcontroller unit(MCU)to measure PBFT,a RFID module to identify each pig and send data(e.g.identity,measurement time and PBFT)to a server via wireless transmission module,and an ultrasonic transducer to drive and receive signals between them.A measurement error within 0-1 mm was acquired through testing three groups of samples.Results indicated that this handheld terminal had a required accuracy and proved that the ultrasonic wave processing method can be deployed in a mobile terminal for PBFT measurement.It also provided a feasible nondestructive alternative to measure PBFT.Associated with information management software platform,this method may ultimately help pig production farmers measure the PBFT accurately and conveniently,and improve the pig production efficiency.

Research exploring greenhouse environment control over the last 50 years

Environments do not exist in isolation.Their main components in greenhouse systems are plants.Without consideration of plants,analysis of greenhouse environments and environmental control of greenhouses can be accomplished,although it is not simple to achieve.Initial attempts were undertaken to analyze greenhouse environments and then reproduce them.Ventilation rate effects on plant photosynthesis in a growth chamber were reported in 1966.Computer simulations then became a main subject of research.The first dynamic computer simulation of a greenhouse environment including plants was published in 1971.According to innovations of computer technology,the use of minicomputers and microcomputers spread in many areas.By measuring the net photosynthesis of lettuce plants grown under artificial lighting,air temperature was optimized using a minicomputer with the hill-climbing method.The method was designated as the Speaking Plant Approach to environment control(SPA).After the author developed the first reported environmental control system in Japan,systems using microcomputers spread widely for greenhouse environmental control.Knowledge-based expert systems were tested for plant management.Also,a machine vision system was developed to detect critical moments for watering of muskmelon plants.The first feed-forward control method for greenhouses with a large heat mass was reported.Then space farming was tested in 1996 to assess gravity effects on plants.Energy-saving aspects such as solar sterilization,ground heat storage system,and storage using phase change material(PCM)have been reported.Defects of ordinary solarimeters were reported in 2008 along with an approach to estimate evapotranspiration in a greenhouse without the effect of so-called cosine law.Later,this technique was expanded to estimate photosynthesis of the plant canopy in a greenhouse using newly developed sensor units.

Bessel-beam-based side-view measurement of seven-core fibre internal core distribution

Accurate knowledge of the internal core distribution of multicore fibres(MCFs)is essential,given their widespread application,including in fibre splicing,bundle fan-in/fan-out,mode coupling,writing gratings,and fibre drawing.However,the extensive use of MCFs is restricted by the limited methods available to precisely measure the fibre core distribution,as the measurement accuracy determines the performance of the product.In this study,a side-view and nondestructive scheme based on Bessel beam illumination was proposed for measuring the internal core distribution of a seven-core fibre.Bessel beams offer a large focal length in a scattering medium,and exhibit a unique pattern when propagating in an off-axis medium with a spatially varying refractive index.The results revealed that a long focal length and unique pattern influence the image contrast in the case of Bessel beams,which differs from a typical Gaussian beam.Further,high-precision measurement of a seven-core fibre core distribution based on a Bessel beam was demonstrated using a digital correlation method.A deep learning approach was used to improve the measurement precision to 0.2°with an accuracy of 96.8%.The proposed side-view Bessel-beam-based method has the potential to handle more complex MCFs and photonic crystal fibres.