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991.
Estimating power-frequency characteristics in power systems by means of spectral analysis techniques
Shigeo Hayashi Akira Kawata Takashi Nagasawa Naoto Yokoyama 《Electrical Engineering in Japan》1993,113(4):78-88
This paper shows that normal power system operating data may be used to determine the power-frequency characteristics in power systems. Data are processed as random signals using spectral analysis techniques, and the results estimate the generator and load power-frequency characteristics as transfer functions. The generator characteristics Kg are determined as a transfer function of the system in which input signals are frequency fluctuation ΔF and generator power setting signal ΔPg, and output signal is generator power output ΔPe, To estimate the load characteristics Kl, a difficulty arises. There is a relation ΔP/ = ΔLo + KlΔF between actual load ΔPl, ideal load under the state of nominal frequency ΔLo, and fluctuation of system frequency ΔF. Because it is impossible to measure ΔLo directly, ΔLo and KlΔF cannot be separated. With regard to a partial system, when its capacity is small enough compared with the total system capacity, the contribution of ΔLo in a partial system to ΔF of the total system may be ignored, that is, ΔF and ΔLo are considered as independent phenomena. Thus the cross spectrum of ΔF and ΔLo decreases to zero according to the increase of data in number, and Kl of the partial system can be estimated. 相似文献
992.
Mechanical properties of poly(vinyl chloride)-poly(acrylonitrile-co-butadiene) blends with modulated structure 总被引:1,自引:0,他引:1
By solution-casting we prepared poly(vinyl chloride)-poly(acrylonitrile-co-butadiene) blends with a modulated structure (a co-continuous two-phase structure with periodic distance of a few micrometres or less). Mechanical properties of the film specimens were investigated by the uniaxial tensile test combined with small-angle light scattering. A 50: 50 plastic-rubber blend has a high initial modulus which is close to that of the rigid plastic. Nevertheless, it can deform to a large extension ratio up to 6. It cannot immediately recover to its original length after the stress-strain test, i.e. residual strain in the stress-strain curve persists. However, after release from the instrument the film gradually shrinks to its original length at room temperature. After strain recovery the film shows a stress-strain curve almost identical to the original. It seems that the stretched film healed simply by resting at room temperature. Based on the light-scattering studies, a helical spring model is derived for the two-phase system with modulated structure, exhibiting the characteristic mechanical properties mentioned above. The spring model interprets well the dependence of Young's modulus on the blend composition and the periodic distance of the modulated structure. 相似文献
993.
Takashi Oozeki Toshiyasu Izawa Kenji Otani Kosuke Kurokawa 《Solar Energy Materials & Solar Cells》2003,75(3-4):687-695
Data evaluation methods have wide adaptations, such as feedbacks to PV system operation management and design. The authors have already developed sophisticated verification method (SV method) of PV systems, which is a simple evaluation method to identify six kinds of system loss rates using basic information and simple four measurable data. This time, the authors introduced quality diagnosis to our previous model for compensating the measurement errors in field data, and improved the algorithm of the model. Consequently, validity of the evaluation result became better than the previous model. 相似文献
994.
Takashi Goto Chen-Yan Guo Hajime Takeya Toshio Hirai 《Journal of Materials Science》1992,27(9):iii-iii
995.
Kazuo Tsutsui Ruifei Xiang Takashi Shiozawa Yasutoshi Okuno Masafumi Kubota Hiroshi Iwai 《Microelectronic Engineering》2008,85(2):315-319
The annealing conditions causing an irregular peak in sheet resistance of nickel silicides are investigated. It is found that the irregular rise in sheet resistance occurs at a critical temperature of 750-775 °C as a result of agglomeration related to phase transition from NiSi to NiSi2. Experiments on the effect of temperature, heating rate and annealing duration in rapid thermal annealing revealed that the high-resistance state produced by annealing at the critical temperature could not be changed by subsequent annealing at higher temperature, and that the high-resistance state required 30-40 s at the critical temperature to form. Pre-annealing at 600 °C was found to suppress the later formation of the high-resistance state. 相似文献
996.
This study proposes a prototype quantitative method for dynamic revenue management of a private toll road, taking into account
the long-term dynamics of transportation demand. This is first formulated as a stochastic singular control problem, in which
the manager can choose the toll level from two discrete values. Each toll change requires nonnegative adjustment costs. Our
analysis then reveals that the optimality condition reduces to standard linear complementarity problems, by using certain
function transformation techniques. This enables us to develop an efficient algorithm for solving the problem, exploiting
the recent advances in the theory of complementarity problems. 相似文献
997.
The stoichiometry of chemical oscillation systems, especially that of the Oregonator proposed by Field and Noyes (1974), is discussed with use of the generalized stoichiometric number theory by Horiuti and Nakamura (1957). The independent stoichiometric equations derived by Noyes (1976) are shown to correspond to Horiuti and Nakamura's reaction routes, each of which was expressed in terms of a set of stoichiometric numbers. It is found that the relations derived by Noyes are partly incorrect. 相似文献
998.
Yoshitomo Uwamino Takashi Nakamura Akihisa Hara 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,239(2):299-309
Two types of multi-moderator neutron spectrometers were developed; one is a gamma-ray insensitive type, and the other is a high-efficiency type. An indium activation detector is loaded in the former spectrometer, which can measure the photon-dominant pulsed neutron field such as in the primary photon beam of a high-energy medical electron accelerator. The latter, in which a 3He counter is loaded, is so sensitive that it can measure leakage neutrons from a well shielded facility or even the skyshine neutrons. The response functions of the spectrometers were measured by thermal and mono-energetic neutron standard fields, and were also calculated by the one-dimensional discrete ordinates transport code, ANISN. The measured and calculated responses showed generally good agreement. A benchmark measurement of 252Cf fission neutrons by using these two spectrometers agreed well with the calculated spectrum. The spectrometers were used in the measurements of neutrons produced by a medical electron accelerator and of skyshine neutrons from an intense 14 MeV neutron source facility. 相似文献
999.
In this paper, discussion is made on the strength of joints combining adhesives with bolts. The stress distributions in adhesives and the variation in bolt axial force are analyzed when an external load is applied to the combination joint. The joint consists of two hollow cylinders clamped by a bolt and a nut with an initial clamping force after they are joined by an adhesive. The analytical result is almost consistent with the experimental result, therefore the strength of the combination joints can be estimated. The strength of the combination joint is greater than that of the adhesive joint. In addition the variation in bolt axial force in the combination joint is less that that in the bolted joint. The characteristics and the availability of combination joints are made clear. 相似文献
1000.
Shin'ichiro Asayama Hideo Ogawa Takashi Noguchi Kazuji Suzuki Hiroya Andoh Akira Mizuno 《Journal of Infrared, Millimeter and Terahertz Waves》2004,25(1):107-117
We have developed an integrated sideband-separating SIS mixer for the 100 GHz band based on the waveguide split block. The measured receiver noise temperatures with 4.0–8.0 GHz IF are less than 60 K in the LO frequency range of 90–110 GHz, and a minimum value of around 45 K is achieved at 100 GHz. The image rejection ratios are more than 10 dB in the frequency range of 90–110 GHz. We have installed the sideband-separating SIS mixer into an atmospheric ozone-measuring system at Osaka Prefecture University and successfully observed an ozone spectrum at 110 GHz in SSB mode. This experimental result indicates that the sideband-separating SIS mixer is very useful for astronomical observation as well as atmospheric observation. 相似文献