Method For Direct Conversion Research Articles

Flat-panel detectors in X-ray systems

For all application segments X-ray systems with flat-panel detectors increasingly enter the market. In digital radiography,mammography and cardiologic angiography flat-panel detectors are already well established while they are made ready for market introduction in general angiography and fluoroscopy. Two flat-panel detector technologies are available. One technology is based on an indirect conversion process of X-rays while the other one uses a direct conversion method. For radiography and dynamic applications the indirect method provides substantial advantages, while the direct method has some benefits for mammography. In radiography and mammography flat-panel detectors lead to clear improvements with respect to workflow, image quality and dose reduction potentials. These improvements are fostered by the immediate availability of the image, the large dynamic range and the high sensitivity to X-rays. New applications and the use of complex image processing algorithms have the potential to enlarge the present diagnostic range of applications. Up to now, image intensifiers are still the well-established technology for angiography and fluoroscopy. Nevertheless flat-panel detectors begin to enter this field, especially in cardiologic angiography. Characteristics of flat-panel detectors such as the availability of distortion-free images, the excellent contrast resolution, the large dynamic range, the high sensitivity to X-rays and the usability in magnetic fields provide the basis for improved and new diagnostic and interventional methods.

Relation Between Electric Power and Temperature Difference for Thermoelectric Generator

The thermoelectric generation is the direct energy conversion method from heat to electric power. The conversion method is a very useful utilization of waste energy because of its possibility using a thermal energy below 423K. This research objective is to establish the thermoelectric technology on an optimum system design method and efficiency, and cost effective thermoelectric element in order to extract the maximum electric power from a wasted hot water. This paper is considered in manufacturing a thermoelectric generator and manufacturing of thermoelectric generator with 32 thermoelectric modules. It was also found that the electric voltage of thermoelectric generator with 32 modules slowly changed along temperature differences and the maximum power of thermoelectric generator using thermoelectric generating modules can be defined as temperature function.

An improved method for direct conversion of heteroaryl-aldehydes to heteroaryl-acetonitriles

Treatment of heteroaryl-aldehydes with diethyl cyanophosphonate in the presence of a catalytic amount of LiCN affords phosphorylated cyanohydrins which are reduced in situ with SmI 2 to give heteroaryl-acetonitriles in generally good overall yields (50–100%). The generality of the process is demonstrated.

次世代超硬質材料の超高圧合成とナノ組織制御 高純度ｃＢＮ多結晶体の微細組織制御による特性向上

Properties of polycrystalline materials strongly depend on their microstructural features such as the grain size distribution, the boundary condition and so on. In this paper, we provide our works concerning microstructural features and some properties of high-purity polycrystalline cBN synthesized from hBN by the direct conversion method. A fine-grained ( 99.9%) with the highest mechanical properties can be obtained by controlling temperature conditions within 2200-2400°C at 7.7 GPa. Many cBN grains rapidly become larger at temperatures above these conditions, and a considerably inhomogeneous microstructure which causes the deterioration of mechanical properties is formed.

Lasing on the 5s2 2D5/2 → 5p 2P3/2 Cd II ion transition upon sputtering of metal cadmium by nuclear particles

A basically new method for direct conversion of the energy of nuclear reactions into laser radiation is considered. The method is based on the use of the emission of excited ions (or atoms) produced by bombarding a solid by charged particles produced in nuclear reactions. The results of an experimental study of the emission of excited Cd II ions and Cd I atoms are presented for metal cadmium irradiated by α particles from 238Pu. When cadmium was heated to a temperature T > 160°C (at least 0.5 Tm, where Tm is the melting temperature), the emission of Cd II ions, which are predominantly in the 4d9 5s2 2D5/2,3/2 states, and resonantly excited Cd I atoms was observed.

2825 高純度 cBN 多結晶体の微細構造と切削性能

High-purity Polycrystalline cBN can be synthesized from hBN by the direct conversion method under HPHT condition without additives or catalyst. Such polycrystalline cBNs under various conditions were prepared and investigated to clarify the effect of impurities and microstructure on cutting performance of the materials. When the amount of the compressed hBN exceeded 0.5%, the cutting performance was found to deteriorate rapidly in high-speed interrupted cutting test of gray cast iron. The tool life of polycrystalline cBN of coarse grade (1-5μm) was found to be shorter than that of fine grade (<0.5μm) by the breakage of the tool edge. From TEM observation, it was found that coarse cBN grains have crystal defects and straight grain boundaries, which are thought to weaken the mechanical strength. It was confirmed that the reduction of remaining compressed hBN (<0.5%) and the suppression of coarsening of cBN grain (<1μ1) are necessary for polycrystalline cBN having excellent performance.

高純度ｃＢＮ多結晶体の微細構造と特性

Microstructural features and some properties of high-purity polycrystalline cBN synthesized from hBN by the direct conversion method were investigated. A fine-grained (<0.5μm) and homogeneous high-purity polycrystalline cBN was obtained at 7.7GPa and 2200-2400°C. At lower pressure and lower temperature than these conditions, compressed hBN remained in the polycrystalline sintered body. Some cBN grains became larger rapidly at higher temperature above 2400°C, and inhomogeneous microstructure was formed. The fine-grained and homogeneous polycrystalline cBN had higher hardness and TRS, compared with the coarse-grained and inhomogeneous polycrystalline cBN. The thermal conductivity of the polycrystalline cBN increased with increasing grain size or synthesis temperature. The thermal conductivity of the fine-grained polycrystalline cBN, however, was 3 to 4 times higher than conventional cBN compacts containing binder materials. The fine-grained and homogeneous high-purity cBN is expected to have high potential in cutting tool applications because of its excellent mechanical and thermal properties.

Impedance analyser module for EIT and spectroscopy usingundersampling

In this paper we present the concept, the design and the test procedure for aDSP-based high-precision and high-performance wide-band (up to 10 MHz)bioimpedance analyser module for application in EIT or bioimpedancespectroscopy. The module implements a digital concept with appropriate signalconditioning hardware for voltage and current measurement, early signaldigitization and subsequent digital signal processing in order to calculatethe components of impedance (or admittance). At low frequencies, the moduleutilizes the conventional direct conversion method, whereas at highfrequencies the undersampling technique is used. The advantages of thedescribed system are the following: (a) the frequency range is extended tohigher frequencies, (b) the number of data sampled per time interval issignificantly reduced, and (c) the current consumption and the costs of theADCs can be significantly reduced.The validation procedure is performed by comparing the measured andtheoretical values of the magnitude and the phase of the impedance for acommonly used tissue model. The module offers an accuracy of better than0.012% for the magnitude of impedance and better than 0.02° for thephase.

Mechanical properties of high purity polycrystalline cBN synthesized by direct conversion sintering method

Mechanical properties of high purity polycrystalline cBN sintered bodies synthesized by the direct conversion method under high pressure and high temperature have been investigated by hardness and transverse rupture strength (TRS) measurement in the temperature range of 20–1200 °C. It was confirmed that the hardness and TRS of the polycrystalline cBN depends strongly on the cBN grain size and the amount of residual (compressed) hBN in the sintered body. The fine-grained ( 99.9%) polycrystalline sintered body synthesized at 7.7 GPa, 2200–2400°C has highest hardness and TRS at any temperature. The TRS of the sintered body shows a positive temperature dependence up to 1200 °C. The high hardness and high TRS at high temperature of the fine-grained high purity polycrystalline cBN suggest that the sintered body has high potential in cutting tool uses.

Pipelined CORDIC processors for generating Gaussian random numbers

This paper proposes a pipelined array for efficient generation of Gaussian random numbers. Since the direct conversion method is used instead of the central limit theorem method, the hardware generation requires only one pair of uniformly distributed sequence as its input. The proposed hardware can also be used to generate Rayleigh-distributed random numbers.

Cyclic Behaviors under Thermal and Loading-unloading Conditions in TiNiCu Shape Memory Alloy. Influence of Strains on Cyclic Behaviors under the Constant Heating and Cooling Temperature.

Use of a heat engine of which the working elements consists of a shape memory alloy is a useful method for direct conversion of power from low grade heat. The authors have proposed a reciprocating heat engine using shape memory alloy wires. However, in order to undertake reliable engineering designs and optimum material selection, it is imperative that the cyclic behaviors of the shape memory alloy are well understood. In this paper, the cyclic behaviors of Ti-41.7 at% Ni-8.5 at% Cu are investigated experimentally. Experiments are carried out by repeating the combination of the thermal cycle and the loading-unloading cycle under the constant heating and cooling temperature. The results show that the transformation temperatures of Mf and As almost do not vary with the number of cycles, but Ms and Af temperatures increase gradually with cycles when the number of cycles is greater than about 500. It is also noted that two-way strain and irrecoverable strain increase proportionately with the increase in maximum strain. Furthermore, from results of deformation stress in the martensitic phase, the plastic deformation is recognized in the strain range of boyond 4%.

Ultrafast time-to-space conversion of phase by the method of spectral nonlinear optics

We propose a method for direct conversion of an ultrashort pulse into a monochromatic beam whose wave front either repeats or is related to the phase structure of the pulse or its spectrum. This can be done by sum-frequency generation of the spectrally resolved pulses. Experimentally, we projected two spectra of the same chirped pulse onto the nonlinear crystal so that the dispersions were opposite. After sum-frequency generation, a converging or diverging monochromatic beam was formed that was the analog of the pulse spectrum. We could determine the chirp value by the measurement of the wave-front radius.

Production of composites on the base of AlCu4 alloy chips

This paper describes the experience obtained with the chips of Al and its alloy with addition of small amount of tungsten powder directly converted into the final product by hot extrusion process. The mechanical and physical properties of Al and AlCu4 based composites are presented. The effect of tungsten contents and heat treatment on the properties is described. Direct conversion method do not harmfully affect an environment and produced material can be used as a final product or can be further processed by another plastic working methods like forging or rolling.

Preliminary Studies of Direct Energy Conversion in a D-3He Inertial Confinement Fusion Reactor

AbstractA direct energy conversion method is proposed for a D-3He inertial confinement fusion reactor. The method utilizes inductive energy recovery through pickup coils in the plasma chamber in which mirror magnetic fields are applied. A method to reduce the problems regarding the handling of ultrahigh voltage inherent in energy recovery of this type is proposed that divides a one-turn pickup coil into a number of pickup segments both axially and azimuthally to reduce the output voltage per pickup segment so that it can be managed by near-term technologies.Analytical results predict that the expanding plasma energy is directly converted to electricity through the recovery circuit using capacitors with an efficiency of >80% when the plasma is assumed to expand cylindrically.

A novel method for direct conversion of tetrahydropyranyl ethers into t-butyldimethylsil ethers with t-butyldimethylsilyl triflate and dimethyl sulfide

Direct conversion of THP ethers into TBS ethers has been achieved with TBSOTf and dimethyl sulfide in dichloromethane.

A novel method for direct conversion of carboxylic acids to 1,3-dithianes by 1,3,2-dithiaborinane-dimethyl sulfide and stannous chloride

A novel method for direct conversion of carboxylic acids to 1,3-dithianes by 1,3,2-dithiaborinane-dimethyl sulfide and stannous chloride

ChemInform Abstract: NEW METHOD FOR DIRECT CONVERSION OF AMIDES TO AMINES

Chemischer InformationsdienstVolume 10, Issue 37 Preparative Organic Chemistry ChemInform Abstract: NEW METHOD FOR DIRECT CONVERSION OF AMIDES TO AMINES A. RADHAKRISHNA, A. RADHAKRISHNASearch for more papers by this authorM. E. PARHAM, M. E. PARHAMSearch for more papers by this authorR. M. RIGGS, R. M. RIGGSSearch for more papers by this authorG. M. LOUDON, G. M. LOUDONSearch for more papers by this author A. RADHAKRISHNA, A. RADHAKRISHNASearch for more papers by this authorM. E. PARHAM, M. E. PARHAMSearch for more papers by this authorR. M. RIGGS, R. M. RIGGSSearch for more papers by this authorG. M. LOUDON, G. M. LOUDONSearch for more papers by this author First published: September 11, 1979 https://doi.org/10.1002/chin.197937149Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue37September 11, 1979 RelatedInformation

New method for direct conversion of amides to amines

New method for direct conversion of amides to amines

A synthetic method for direct conversion of ketones into cyanides. Introduction of a one carbon unit.

A synthetic method for direct conversion of ketones into cyanides. Introduction of a one carbon unit.

Detection Process in Neutron Radiography

A model of the imaging process in the direct conversion method for obtaining neutron radiographs is presented. The analysis is aimed at obtaining expressions for the attainable object resolution as a function of system and object parameters. Initially, the analysis is carried out assuming a parallel incident beam of neutrons in order to compute the best possible resolution. The results obtained are subsequently used to elucidate the effect of varying certain detection system parameters on both the resolution function and the relative exposure times for a gadolinium converter. Since the neutron beams used in radiography cannot generally be considered to be sufficiently close to parallel, the model has been extended to allow the incorporation of the effects of neutron beam divergence due to finite source size. Comparisons are presented between the results obtained from this model of the neutron radiographic process and experimental data already reported in the literature.