巧用“虚短”和“虚断”分析电路谐振

众所周知,“虚短”和“虚断”是模拟电子技术中分析运放电路的重要手段.然而,作者在多年的教学与实践中发现,该方法同样可以巧妙地用于“电路分析基础”中谐振相关问题的分析,而且该技巧简单直观,可以免去复杂的复数运算,应用起来方便快捷.本文通过理论分析和实例验证了所提方法的有效性,在相关电路分析中具有一定的价值.

Virtual fracture test of asphalt mixture based on discrete element method

In order to study fracture behaviors of asphalt mixtures, virtual tests of the two-dimensional（2D） microstructure based on the discrete element method（ DEM） are designed. The virtual structure of the 2D digital specimen of asphalt mixture is generated based on a particle generation program, in which the gradation and the irregular shapes of aggregates are considered. With the 2D digital specimens, a DEM-based mixture model is established and center-point beam fracture simulation tests are conducted by the DEM. Meanwhile, a series of calibration tests are carried out in laboratory to evaluate the DEM model and validate the methods of virtual fracture tests. The test results indicate that the fracture intensity of asphalt mixtures predicted by the DEM matches very well with the intensity obtained in laboratory. It is concluded that the microstructural virtual tests can be used as a supplemental tool to evaluate fracture properties of asphalt mixtures.

Comparison of virtual colonoscopy and colonoscopy in diagnosis of colorectal neoplasia

The diagnostic value of virtual colonoscopy versus colonoscopy was compared in detection of colorectal neoplasia. Virtual colonoscopy was performed on 29 patients with suspected colorectal diseases, Results were compared with colonoscopy for each case. Virtual colonoscopy was successfully performed on each patient. All patients tolerated virtual colonoscopy well, had no complications. All colorectal malignance were identified both by virtual colonoscopy and colonoscopy. Twenty-five polyps were detected with colonoscopy, whereas only 16 polyps were defined by virtual colonoscopy. Detection rates of polyps greater than 1.0 cm,between 0.5-0.9 cm and less than 0.5 cm in size were 90%,62.5% and 28.6% respectively. Virtual colonoscopy is fast, minimally invasive and well tolerated. This technique is a valuable clinical method in diagnosis of colorectal malignance and polyps larger than 0.5 cm in size.

New Approach for Calculating Tomograms of Quantum States by Virtue of the IWOP Technique

We show that for tomographic approach there exist two mutual conjugate quantum states [p,σ, τ） and [x,μ, ν） （named the intermediate coordinate-momentum representation）, and the two Radon transforms of the Wigner operator are just the pure-state density matrices [p）σ1τσ1τ （p｜ and （p）λ,ν,λ,ν,（x｜ respectively. As a result, the tomogram of quantum states can be considered as the module-square of the states＇ wave function in these two representations. Throughout the paper we fully employ the technique of integration within an ordered product of operators. In this way we establish a new convenient formalism of quantum tomogram.

Wedge Splitting Test and Inverse Analysis on Fracture Behaviour of Fiber Reinforced and Regular High Performance Concretes

The fracture behaviour of three fiber reinforced and regular HPC （high performance concretes） is presented in this paper. Two mixes are based on optimization of HPC whereas the third mix was a commercial mix developed by CONTEC ApS （Denmark）. The wedge splitting test setup with 48 cubical specimens was used experimentally and the cracked non-linear hinge model based on the fictitious crack model was applied for the interpretation of the results. The stress-crack opening relationships were extracted by using inverse analysis algorithm for various multi-linear softening curves. This showed that the refinement of the softening curves reflects in improved accuracy of the WST （wedge splitting test） simulation in comparison with bi-linear softening curves with acceptable increase of computational time. Furthermore, the fracture mechanics parameters such as COD （crack opening displacement）, fracture energy and characteristic length were experimentally determined. Experiments were performed at 1, 3, 7 and 28 days. Fracture energy, Gf, was found to increase with age, while the characteristic length, Lch, was found to decrease.

Traditional Chinese Medicine diagnoses in persons with ketamine abuse

OBJECTIVES： To explore the distribution of TCM patterns in ketamine users and the inter-rater reli- ability of TCM diagnosis among TCM practitioners. METHODS： Eighty-four subjects recruited from sub- stance abuse clinics and non-governmental coun- seling services catering for ketamine abusers were examined by one or two TCM practitioners. The dis- tribution and inter-rater reliability of the TCM diag- noses between the two TCM practitioners were de- scribed and measured. RESULTS： Seven TCM patterns were differentiated. The four most common patterns were the Heart Yin deficiency （29.8%）, Kidney Yang deficiency （26.2%）, Kidney Yin deficiency （19.0%）, and Spleen Yang defi-ciency （14.3%）. The agreement between the two TCM practitioners was 59%, the kappa for the three most common patterns was 0.472 （P=O.O03）. The proportion of men was lower in the Kidney Yin defi- ciency group （18.8%）, in comparison to the Heart Yin deficiency （60.0%, P=0.009） and Kidney Yang de- ficiency group （59.1%, P=0.013）. CONCLUSION： The differences between the TCM groups in terms of the source of referral and num- ber of drug uses other than ketamine were of bor- derline significance. Further research should focus on validating diagnostic tools and improving in- ter-rater reliability in TCM to enhance the quality of clinical trials of TCM treatments for ketamine abuse.