CHARACTERISTICS OF HEAT TRANSFER FROM A SPHERICAL SOLID BODY UNDER PULSATING FORCED CONVECTION

Heat transfer from a solid sphere having a Biot number Bi ? 0.1 to a flow medium in a cooling process under pulsating forced convection is experimentally examined. In the experiment, two kinds of pulse modes, which are the type of pulsating forced convection with continuous feed and the feed type mixing forced and natural convection, are considered as a pulse feed technique. Initially, the evaluation method of the Nusselt number Nu is derived in the cooling process and the validity of that method is verified by comparison with the experimental results. With regard to the effect of pulsating feed, it is shown that the pulsating feed conditions have a great influence on the characteristics of the heat transfer. The enhancement of heat transfer under the condition of the forced convection pulsatively fed with continuous feed is recognized, and the characteristics of heat transfer for the pulsating feed including natural convective heat transfer region are aggravated. Besides, it is clear that the decrease in the heat transfer characteristics is dependent on the duration of the natural convective heat transfer. Furthermore, Ranz-Marshall correlations for each pulsating feed condition are presented.     

Anionic Conduction in Lead Halosilicate Glasses

Electrical conductivity due to halide ions has been measured for the glasses in the system 30SiO₂· (70 − x )PbO · x PbX₂ (0 < x < 17.2 mol%; X = F, Cl). The conductivity increases with x by several orders of magnitude for both series of glasses. The contribution of principal factors to the conductivity has been examined. The analysis of the activation energy on the basis of the Anderson-Stuart model shows that the strain energy is a predominant term in the Cl glasses, while both the strain energy and the electrostatic energy have a comparable contribution in the F glasses. The decrease in the activation energy with increasing PbX₂ content is related to the decrease in the shear modulus for the Cl glasses and to the increase in the permittivity for the F glasses.     

栏栅式山溪取水工程取水特性的试验研究

通过水工模型试验,对栏栅式山溪取水工程的取水特性进行了研究,探讨了在有足够大的集水廊道的前提下,该取水工程的潜在取水能力。结果表明,在影响栏栅取水量的诸因素中,栅条长度、栅隙和栏栅的设置角度对取水量的影响程度不同;其取水量主要由栏栅的设置角度决定,而栅条长度和栅隙对取水量的影响程度较小;栏栅的设置角度小于50°时,栏栅有较大的引水比,栏栅的设置角度大于50°后,栏栅的引水比大幅度下降。     

Bioluminescence microscopy using a short focal‐length imaging lens

Bioluminescence from cells is so dim that bioluminescence microscopy is performed using an ultra low‐light imaging camera. Although the image sensor of such cameras has been greatly improved over time, such improvements have not been made commercially available for microscopes until now. Here, we customized the optical system of a microscope for bioluminescence imaging. As a result, bioluminescence images of cells could be captured with a conventional objective lens and colour imaging camera. As bioluminescence microscopy requires no excitation light, it lacks the photo‐toxicity associated with fluorescence imaging and permits the long‐term, nonlethal observation of living cells. Thus, bioluminescence microscopy would be a powerful tool in cellular biology that complements fluorescence microscopy.     

Effect of concrete buildings on the environmental neutron flux by using the reaction^197 Au （n,γ）^198Au and extremely low level gamma ray spectroscopy

The activation of gold by environmental neutrons through the reaction^197Au (n,γ)^198Au was used to study the effect of concrete buildings on the neutron flux, and to estimate the thermal neutron flux inside and outside these buildings. The results showed that three ceilings of thickness 34 g/cm^2 decrease the fast neutrons to 26% from its original value. However, the same reinforced concrete decreases the slow neturon flux to only 62% of its original value. The thermal neutron flux at 283 m from the center of Training Reactor of Kinki University, was twice higher than the environmental neutron background.     

A Study on the Power System Security under Future Uncertainties

In this paper, we propose three applications to quantitatively evaluate N‐1 security with increased uncertainties. By using a robust dynamic security region (RDS), which is based on the concept of robust power system security (RS), the key region for judging the security and a new evaluation index for quantitative analysis, we can evaluate power system security as follows. (1) The calculation of the RDS at the time of yearly peak load demand can be recognized as the benchmark for the N‐1 security at present, and this method can be applied to the future power system with increased renewable energy resources (RES) such as PV. (2) We show the yearly declining trend for N‐1 security resulting from increased PV deployment year by year. (3) We calculate the necessary amount of additional power supply capacity, including conventional electric power generators or storage batteries, needed for maintaining the N‐1 security at the present level. The effectiveness of the proposed method is demonstrated through simulations using a model system with three machines.     

Machine of testing the ceramic&#8217;s bending strength properties at high temperature and ultra-low speed

According to the established rules for testing ceramic’s bending strength, the falling velocity of the pressure head of the machine should be more than 0.5 mm/min. For the machine of testing the ceramic’s bending strength properties, most designs adopt the lowest falling velocity as 0.5 mm/min. In the fields such as aerospace and deep-ocean exploration, the utilization of ceramic materials that work at normal temperature, low temperature, or even high temperature and bend at an ultra-low velocity is increasing; thus, the intense requirements for the machine of testing the ceramic’s bending strength properties at high temperature and ultra-low speed (MTCBSP) and its experimental basis are put forward. This research developed an MTCBSP suitable for normal temperature and high temperature with the lowest falling velocity of 0.05 mm/min, and manufactured a drive reducer for ultra-low speed and high-temperature working condition. In the test, equipment includes a high-temperature furnace, bending die for four-point bending, and protection system of inert gas, which was placed in the high-temperature furnace to prevent the ceramic sample from being oxidized to diminish its effects. The results show that the lowest falling velocity of the pressure head of this new machine is 0.05 mm/min, and the mechanical properties of silica glasses are noticeably different at the same high temperature and the different falling velocities of 0.5 mm/min and 0.05 mm/min.     

Variation of environmental neutron flux with altitude and depthof both water and soil

Applying the extreme low-level y-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction ^197Au (n, γ) ^198Au- The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.     

Development of High‐Acceleration Linear Motor to Realize Resource Saving and High Productivity

The use of linear motors has been rapidly increasing in recent years in response to the rising demand for drive mechanisms with higher speed and acceleration to improve the throughput of semiconductor production equipment, machine tools, and so on. In this study, we have developed a new type of linear motor with an opposed magnetic pole structure and twin movers. To achieve higher acceleration of a linear motor, it is necessary to satisfy both large thrust and low inertia. In our proposed new type linear motor, the thrust is improved by increasing the facing area between the permanent magnets and magnetic pole teeth by using multistage movers. Furthermore, the magnetic leakage flux is reduced by multiplexing the magnetic flux path. In a short stroke (approximately 210 mm) drive, the high acceleration of 1670 m/s² and maximum velocity of 14.2 m/s is demonstrated using a prototype linear motor (maximum thrust = 25 kN).