Acquisition Behavior of a First-Order Digital Phase-Locked Loop

A general "phase-plane" technique for investigating the stability of nonlinear difference equation is described and applied to determine the stability criterion of a first-order digital phase-locked loop (DPLL). If the loop is stable, it is shown that acquisition behavior can be modeled as a first passage time problem. Using this model, one can evaluate the acquisition probability and the mean time to acquire, from the appropriate Chapman-Kolmogorov (C-K) equation describing the transition of the phase error sequence. This approach is verified by direct simulation.     

JAXA-GCF project - high-quality protein crystals grown under microgravity environment for better understanding of protein structure

Since 2003, Japan Aerospace Exploration Agency (JAXA, former NASDA) has been conducting a project on a semi-annual basis (JAXA-GCF) to obtain high-quality protein crystals in the microgravity environment using the Russian transportation system. For this project, protein samples were mostly provided by Japanese users for whom JAXA provided technical and clerical support for crystallization experiments in microgravity. For the project, JAXA has constructed a user-friendly support service for microgravity experiments and provided regular and frequent flight opportunities. To simplify and improve technological matters, JAXA devised a gel-tube method crystallization device, which is effective both in space and on ground, based on the counter-diffusion technique. JAXA also provided ground-based techniques for efficient preliminary optimization of crystallization conditions using a 1-dimensional simulation and for harvesting and cryoprotecting crystals before X-ray diffraction experiments. These improvements have significantly increased the success rate of obtaining useful results. In conclusion, JAXA has developed technologies for growing, in microgravity, high-quality protein crystals, which may diffract up to atomic resolution, for a better understanding of 3-dimensional protein structures through X-ray diffraction experiments.     

Notch effect on torsional fatigue of austenitic stainless steel: Comparison with low carbon steel

Notch effect in austenitic stainless steel under cyclic torsion is quite different depending on the superposition of static tension. In pure torsion, the rubbing of the serrated factory-roof type crack faces delays the crack growth along the notch root. Thus, the lifetime in notched specimen becomes longer than in smooth specimen. However, in cyclic torsion with static tension, the flat crack path and mean tensile stress reduce the influence of the crack face contact. Accordingly, shorter lifetime resulted from higher strain concentration at the notch root. Crack growth in low carbon steel under cyclic torsion is highly affected by the ferrite/pearlite banded microstructure besides the addition of static tension. Because of a small amount of the crack face contact, the reduction of lifetime in notched specimen is revealed irrespective of superposition of static tension.     

Remote calibration of ionization chambers for radioactivity calibration

A new calibration technique, referred to as e-trace, has been developed by the National Institute of Advanced Industrial Science and Technology (AIST). The e-trace technique enables rapid remote calibration of measurement equipment and requires minimal resources. We calibrated radioisotope calibrators of the Japan Radioisotope Association (JRIA) and the Nishina Memorial Cyclotron Center (NMCC) remotely and confirmed that remote calibration provided results that are consistent with the results obtained by existing methods within the limits of uncertainty. Accordingly, e-trace has been approved as the standard calibration method at AIST. We intend to apply remote calibration to radioisotope calibrators in hospitals and isotope facilities.     

Intraoperative monitoring of depth-dependent hemoglobin concentration changes during carotid endarterectomy by time-resolved spectroscopy

By measuring the adult human head during carotid endarterectomy, we investigate the depth sensitivity of two methods for deriving the absorption coefficient changes (Dmu(a)) from time-resolved reflectance data to absorption changes in inhomogeneous media: (1) the curve-fitting method based on the diffusion equation (DE-fit method) and (2) the time-independent calculation based on the modified Lambert-Beer law (MLB method). Remarkable differences in the determined values of Dmu(a) caused by clamping the external carotid artery and subsequently clamping the common carotid artery were observed between the methods. The DE-fit method was more sensitive to mu(a) changes in cerebral tissues, whereas the MLB method was rather sensitive to mu(a) changes in the extracerebral tissues. Our results indicated that the DE-fit was useful for monitoring the cerebral blood circulation and oxygenation during neurosurgical operations. In addition, the combined evaluation of mu(a) changes with the DE-fit and MLB methods will provide us with more available information about the hemodynamic changes in the depth direction.     

Function of glycine during solid-state reaction toward well-crystallized fine particulate barium titanate

Effects of glycine added to BaCO₃ and TiO₂ mixtures were examined during a solid-state reaction toward phase pure BaTiO₃ for MLCC with the average particle size below 180 nm and the tetragonality, c/a, above 1.009. Changes in the states of glycine during heating were monitored by differential thermogravimetry and high-temperature X-ray photoelectron spectroscopy. Glycine residue persists up to around 350 °C and destabilizes Ti–O bonds in TiO₂ prior to the initiation of reaction toward BaTiO₃. This, in turn, leads to a decrease in the reaction termination temperature due to higher mobility of Ba²⁺ ions through the reaction zone.     

给孩子绿色网络

网络已经成为了现代社会不可分割的一部分,生活、学习、工作等部离不开网络。可对于孩子不得不承认网络是把双刃剑：—方面,网络是孩子学习、了解知识的平台;另—方面由于孩子的自控能力不强,加之网络的不健康内容对于孩子身心健康的影响不容忽视。     

Preparation of high-modulus and high-strength poly(ethylene terephthalate) film by zone-annealing method

The zone-annealing method was attempted to prepare high-modulus and high-strength poly(ethylene terephthalate) (PET) film. The film having Young′s modulus of 14.5 × 10¹⁰ dyn/cm² and a tensile strength of 86.9 kg/mm² in the drawing direction was obtained. These values correspond to four times those of a biaxial-stretched PET film available commercially. The dyanmic viscoelastic properties also were measured. The dynamic storage modulus was 15.4 × 10¹⁰ dyn/cm² at room temperature, and a high value of 3.6 × 10¹⁰ dyn/cm² even at 200°C. The latter value is slightly higher than the room temperature modulus of the commercially available film. From the intensity and temperature position of α-dispersion E″ peak, it was suggested that the amorphous chains in the zone-annealed film was densely packed in a highly oriented state. Furthermore, the crystallinity, orientation, especially double orientation, and molecular chain conformation of the films in the zone-annealing process are discussed in the present paper.     

Shape optimization of one‐chamber perforated plug/non‐plug mufflers by simulated annealing method

To economically and efficiently lower the venting noise, the development of a high‐quality muffler with compact volume has become crucial in the modern industrial field. The research work of shape optimization of straight silencers in conjunction with plug/non‐plug perforated ducts which may noticeably increase the acoustical performance is rarely addressed; therefore, the main purpose of this paper is not only to analyze the sound transmission loss (STL) of a one‐chamber plug/non‐plug perforated muffler but also to optimize the best design shape under a limited space. In this paper, on the basis of plane wave theory, the four‐pole system matrix in evaluating the acoustic performance is derived by using the decoupled numerical method. Moreover, a simulated annealing (SA) algorithm searching for the global optimum by imitating the softening process of metal has been adopted during the muffler's optimization. To assure SA's correctness, the STL's maximization of one‐chamber perforated plug mufflers at a targeted frequency of 500 Hz is exemplified first. Furthermore, a numerical case in dealing with a broadband noise emitted from a fan by using one‐chamber plug/non‐plug mufflers has been introduced and fully discussed. To achieve a better optimization in SA, various SA parameter sets of cooling rate and iteration parameter values were used. Before the SA operation can be carried out, the accuracy check of the mathematical models with respect to plug/non‐plug perforated mufflers has to be supported by experimental data. The optimal result in eliminating broadband noise reveals that the muffler with a plug acoustical mechanism has a better noise reduction than that of a non‐plug muffler. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is certainly easy, economical, and quite effective. Copyright © 2007 John Wiley & Sons, Ltd.     

Serving two correlated queues with a synchronous server underexhaustive service discipline and nonzero switchover time

A system composed of two queues that accepts correlated inputs and receives services from a synchronous server is studied. An exhaustive service discipline is adopted in serving a queue. Nonzero switchover time for the server to change service from one queue to the other is assumed. A closed-form expression for mean waiting time is obtained. The validity of the analysis if verified using the results of a computer simulation