Method of all-optical frequency encoded decimal to binary and binary coded decimal, binary to gray, and gray to binary data conversion using semiconductor optical amplifiers

Conversion of optical data from decimal to binary format is very important in optical computing and optical signal processing. There are many binary code systems to represent decimal numbers, the most common being the binary coded decimal (BCD) and gray code system. There are a wide choice of BCD codes, one of which is a natural BCD having a weighted code of 8421, by means of which it is possible to represent a decimal number from 0 to 9 with a combination of 4 bit binary digits. The reflected binary code, also known as the Gray code, is a binary numeral system where two successive values differ in only 1 bit. The Gray code is very important in digital optical communication as it is used to prevent spurious output from optical switches as well as to facilitate error correction in digital communications in an optical domain. Here in this communication, the author proposes an all-optical frequency encoded method of ":decimal to binary, BCD," "binary to gray," and "gray to binary" data conversion using the high-speed switching actions of semiconductor optical amplifiers. To convert decimal numbers to a binary form, a frequency encoding technique is adopted to represent two binary bits, 0 and 1. The frequency encoding technique offers advantages over conventional encoding techniques in terms of less probability of bit errors and greater reliability. Here the author has exploited the polarization switch made of a semiconductor optical amplifier (SOA) and a property of nonlinear rotation of the state of polarization of the probe beam in SOA for frequency conversion to develop the method of frequency encoded data conversion.     

Prediction of Magnetic Susceptibilities in Diamagnetic Binary Fluid Mixtures

A model is proposed to predict magnetic susceptibilities in diamagnetic binary fluid mixtures. The model predictions are compared to experimental information for nine binary systems including polar and non-polar compounds. The predictions are also compared to the results obtained from the traditional Boyer-Donzelot equation. For all systems analyzed, the model predicted magnetic susceptibilities closer to the experimental values than those predicted from the Boyer-Donzelot equation. The deviations from the experimental values decrease when the binary system exhibits a positive excess magnetic susceptibility.     

Integer Representation of Decimal Numbers for Exact Computations

A scheme is presented and software is documented for representing as integers input decimal numbers that have been stored in a computer as double precision floating point numbers and for carrying out multiplications, additions and subtractions based on these numbers in an exact manner. The input decimal numbers must not have more than nine digits to the left of the decimal point. The decimal fractions of their floating point representations are all first rounded off at a prespecified location, a location no more than nine digits away from the decimal point. The number of digits to the left of the decimal point for each input number besides not being allowed to exceed nine must then be such that the total number of digits from the leftmost digit of the number to the location where round-off is to occur does not exceed fourteen.     

Programmable DNA Nanoindicator‐Based Platform for Large‐Scale Square Root Logic Biocomputing

The prospect of programming molecular computing systems to realize complex autonomous tasks has advanced the design of synthetic biochemical logic circuits. One way to implement digital and analog integrated circuits is to use noncovalent hybridization and strand displacement reactions in cell‐free and enzyme‐free nucleic acid systems. To date, DNA‐based circuits involving tens of logic gates capable of implementing basic and complex logic functions have been demonstrated experimentally. However, most of these circuits are still incapable of realizing complex mathematical operations, such as square root logic operations, which can only be carried out with 4 bit binary numbers. A high‐capacity DNA biocomputing system is demonstrated through the development of a 10 bit square root logic circuit. It can calculate the square root of a 10 bit binary number (within the decimal integer 900) by designing DNA sequences and programming DNA strand displacement reactions. The input signals are optimized through the output feedback to improve performance in more complex logical operations. This study provides a more universal approach for applications in biotechnology and bioengineering.     

A New Technique for Designing High-Speed Frequency Counters

Some basic difficulties in the implementation of high-speed frequency counters are discussed. A new method which avoids most of these difficulties is described. The method essentially consists of binary prescaling the input frequency to a value easily manageable with decade counters and subsequently multiplying the resultant count in the decade counters by the prescaling factor. A simple digit serial multiplier for this purpose is iliustrated along with the system design of a 150-MHz frequency counter. Finally, the advantages of the new approach are discussed.     

Image Enhancement of Blurry DR Images Using FLIT-LBP Texture Descriptors

The blurring of DR image often affects defect inspection. In this paper, a novel method called FLIT-LBP for the enhancement of blurry DR image is presented. The proposed method utilizes finite line integral transform (FLIT) to extract direction information, based on which appropriate weight arrangement can be chosen. Weight arrangement is a sorting order of weights that converts binary codes to decimal codes in local binary patterns (LBP). And the central pixel information is extracted by computing the mean value in LBP. By combining the direction extraction of FLIT and the local comparison of LBP, FLIT-LBP is able to enhance blurry defect images with different directions. Experimental results show that FLIT-LBP performs better than LBP and FLIT respectively. In addition, in the case of defects with different contrast ratios lying in the same image, our method achieves better enhancement than grayscale stretch does.     

Influence of counter ion on polyaniline and polypyrrole

The electronic, magnetic, optical and redox properties of conjugated polymers are greatly influenced by structure, electronegativity, solvation and orientation of a counter ion. The doping by counter ion not only creates a band structure but also stabilizes localized bound states to impart unusual optical and magnetic properties to macromolecular system. When the polymer is in contact with solution of an electrolyte, counter ion tends to be solvated and mobile in the polymer phase, imparting it a property of ion exchange membrane. Here we briefly summarize the influence of anion on properties and electrochemical behaviour of polyaniline and polypyrrole.     

Graded bit patterned magnetic arrays fabricated via angled low-energy He ion irradiation

A bit patterned magnetic array based on Co/Pd magnetic multilayers with a binary perpendicular magnetic anisotropy distribution was fabricated. The binary anisotropy distribution was attained through angled helium ion irradiation of a bit edge using hydrogen silsesquioxane (HSQ) resist as an ion stopping layer to protect the rest of the bit. The viability of this technique was explored numerically and evaluated through magnetic measurements of the prepared bit patterned magnetic array. The resulting graded bit patterned magnetic array showed a 35% reduction in coercivity and a 9% narrowing of the standard deviation of the switching field.     

A Hazard-Free Walsh-Function Generator

Outputs of a Gray code counter are used to synthesize digital Walsh functions that are free from hazards. This method, which produces sequency-ordered Walsh functions, also uses a binary code to select the order.     

An experimental study of flux presetting-resetting characteristics of magnetic cores with rectangular hysteresis loop

When magnetic cores with a square hysteresis loop are used for a time delay Crcuit or a pulse counter circuit, and if these circuits are designed by the use of the static hysteresis loop, the ac magnetization curve, or the control magnetization curve (CMC) which is the basic characteristic of a magnetic amplifier, there is apt to be a marked discrepancy between their design values and measured values. Since, in the flux control of magnetic cores used for a time delay circuit or a pulse counter circuit, the flux, contrary to the case with a magnetic amplifier, arrives at the negative saturation from the positive saturation by many intermittent signal voltages, a new characteristic quite different from CMC and other characteristics must be adopted as the standard of the design in this case. It was for this reason that instantaneous relation between the rate of flux change and the exciting current was examined in the case in which real flux resetting behaviors of a time delay circuit or a pulse counter circuit were taken into consideration, by using grain-oriented 50 per cent permalloy as the sample, with a view to obtaining core characteristics serviceable enough for exact design methods of a time delay circuit or a pulse counter circuit. Various useful results have been obtained as to: 1) how the correlation between rate of flux changedPhi/dtand instantaneous values of exciting current icchanges in proportion to the flux values, 2) how the amount of reset fluxDeltaPhi_{r}will change according to the flux valuePhiand the rate of flux changedPhi/dt, and 3) how the above-mentioned relations are connected to the tape thickness of the magnetic core. This paper reports the results of this investigation.     

Do Images of Biskyrmions Show Type‐II Bubbles?

The intense research effort investigating magnetic skyrmions and their applications for spintronics has yielded reports of more exotic objects including the biskyrmion, which consists of a bound pair of counter‐rotating vortices of magnetization. Biskyrmions have been identified only from transmission electron microscopy images and have not been observed by other techniques, nor seen in simulations carried out under realistic conditions. Here, quantitative Lorentz transmission electron microscopy, X‐ray holography, and micromagnetic simulations are combined to search for biskyrmions in MnNiGa, a material in which they have been reported. Only type‐I and type‐II magnetic bubbles are found and images purported to show biskyrmions can be explained as type‐II bubbles viewed at an angle to their axes. It is not the magnetization but the magnetic flux density resulting from this object that forms the counter‐rotating vortices.     

Numerical study on directional solidification of AlSi alloys with rotating magnetic fields under microgravity conditions

A global thermal model of the ARTEX facility, developed with the modeling tool CrysVUn, is presented. The model is validated with experimental data obtained under microgravity conditions during the TEXUS39 mission. Numerical studies are then reported, in which the effects of a rotating magnetic field are investigated during directional solidification of binary AlSi7 alloys. It appears that beyond a certain magnetic field strength a macrosegregation effect is resulting, leading to the development of a liquid channel inside the mushy zone.     

On a method of logic design with branched cores

The maximum evaluation for variations of a signal proportional to a threshold element input composition is calculated. A design procedure is developed for a logical element with an absolute magnitude of its output composition independent of the input code. The method suggested makes it possible to design a complete binary summer on one multiaperture magnetic core.     

稀土(R)—铁合金永磁材料及其在测试技术中的应用

论述了新型R-Fe合金化合物永磁材料的发展及近期成果,针对剩磁、矫顽力、最大磁能积、居里温度等硬磁材料的各项指标,对R-Fe合金永磁材料与传统的铁氧永磁材料、稀土—钴永磁材料等进行了比较和分析,展望了R-Fe永磁材料在测试技术中的应用前景。     

单片机控制的高精度Michelson干涉型波长计

设计了Ⅻehelson干涉型激光波长计干涉条纹的单片微机计数硬件电路,编写了8254计数和KeilC51波长运算程序．为提高仪器的测量精度,在硬件和软件上提出了新的设计方案．两个8254计数器可以在单片微机的控制下自动从参考光脉冲信号的下降沿开始对参考信号和被测信号同时计数;参考激光干涉条纹计数满1500000后。参考信号和被测信号的计数器可以同时被自动锁定;单片微机得到锁定信号后,完成两个计数值的读取、波长运算、10次移位平均和7位波长显示．对633nm和532nm两种稳频激光波长进行了实际测量,测量数据表明该计数系统使波长的测量精度达到2×10^-7．     

Automated measurement of the refractive index of fluids

A method for automating refractive-index measurements of fluids has been developed. An encoded rotation stage and position-sensitive detector enable automated reading of angles typically acquired by visual means. Two tunable lasers are used to obtain index measurements at ten discrete wavelengths across the visible spectrum. This method has been implemented on a Hilger-Chance refractometer from which the bulk refractive-index values for various transparent fluids have been measured. An index measurement accuracy of better than one part in the fourth decimal place for distilled water and a few parts in the fourth decimal place for higher index fluids is obtained.     

A driftless gas proportional scintillation counter for muonic hydrogen X-ray spectroscopy under strong magnetic fields

An experiment involving muonic hydrogen requires an X-ray detector having large area and working under strong magnetic fields (5 T) with good energy and timing resolution. A compact, driftless gas proportional scintillation counter (GPSC) capable of operating under such magnetic fields is investigated. This GPSC uses a CsI photocathode deposited onto a microstrip plate as the UV scintillation readout photosensor. This photocathode has the advantage of operating in direct contact with the scintillation gas. The detector is filled with pure xenon and is designed to have a high detection efficiency for 2 keV X-rays. Energy resolutions of 23% and 22% were obtained for 1.74 and 2.3 keV X-rays, respectively. The low-energy detector limit due to the electronic noise is 300 eV. Its performance in the presence of strong magnetic fields was tested. At magnetic field of 5 T the detector pulse amplitudes are reduced by less than 25%, while the detector energy resolution and pulse rise time present a relative increase of less than 10%.     

The effect of citations on the significance of decimal places in the computation of journal impact factors

Journal impact factors (JIF) are computed by Thomson Reuters to three decimal places. Some authors have cast doubt on the validity of the third decimal place in JIFs. In this paper I present a new approach to evaluate the significance of decimal places in JIFs. To do so, two modified JIFs were computed by adding or removing one citation to the number used by Thomson Reuters to compute the JIF for journals listed in the 2008 Journal Citation Report. The rationale is that one citation is the minimum amount of impact that can be observed and analyzed. Next, the modified JIFs were compared with the original JIF to identify the decimal place that changed as consequence of adding or removing one citation. The results suggest that for about two-third of journals, the number of places used by Thomson Reuters to compute JIFs can be considered appropriate for the most part.     

A bubble string comparator for information processing

A new magnetic bubble device is proposed: the bubble string comparator. It performs the sorting of couples of data without any logical control, depending only on the nature of the couples themselves. By means of an external control the bubble string comparator can also operate as a standard binary switch, either in bypass mode or in cross-over mode.     

Hardware control of an active magnetic shield

The presented hardware controller controls the current in an active shield consisting of a number of compensation coils at well-chosen positions. In combination with a converter and the active shield, the controller reduces the fundamental component of the magnetic stray field of an induction heater by generating a magnetic counter field in a defined target area. The controller uses two input signals (from two magnetic field sensors) and generates amplitude and phase information for the converter. Based on this information, the latter produces the compensation current wave that is sent to the compensation coils to minimise the magnetic field. The frequency range of the controller is 1-100 kHz. Its dynamic behaviour is explained in theory and validated by experiments