Any small decentering of a lens's surface can be resolved into an angular tilt of the surface about its intersection with the optical axis. The decentration error of an optical lens has a significant effect on the quality of the image it produces. This paper presents a simple method based on skew ray tracing and an optical centering device to calculate the decentration error resulting from the surface tilt of an optical lens. The results reveal that the decentration error and the radius of the spot circle traced out on the detector of the optical centering device as the sample of interest is rotated are related via a linear approximation when the decentration error is small. Furthermore, it is found that for small surface tilt angles, an approximate value of the decentration error can be obtained simply by taking the first-order differentiation of the mathematical expression for the decentration error.

View full abstract

This paper synthesizes novel configurations of manually operated dynamo flashlights. Topology and motion characteristics of existing gear dynamos are modified and concluded. The structural sketches and corresponding graph representations for gear trains and dynamos with the defined induced magnetic circuits are defined. Through the concepts of generalization and specialization, the atlas of the structural sketches and graphs of the embedded gear dynamos is obtained subject to the defined design requirements and constraints. And, a systematic approach is proposed to synthesize the novel mechanisms of the embedded gear dynamos. As a result, the embedded three-link and four-link gear dynamos have 12 and 24 novel design configurations, respectively. One prototype of the embedded three-link and another of the embedded four-link gear dynamo are built.

View full abstract

In the rough cutting process of sculptured surface machining, using rough cutting models, which are composed or large flat facets and have simple shape profiles, could effectively reduce the machining time and improve the machining efficiency. In this paper, a 3D rough cutting model generation algorithm for sculptured surface machining is presented. The proposed algorithm is based on offset and multi-resolution mesh. Offset guarantees that the rough cutting models always involve the input model, while multi-resolution mesh allows the simplification of a complex model into coarser approximations. This proposed algorithm could generate 3D rough cutting models with different resolutions from the input model. These models have simple geometric complexities and incremental volume changes. The experimental results indicate that the generated rough cutting models are suitable for rough cutting process in sculptured surface machining.

View full abstract

A novel experimental method has been developed to quantify the breakdown processes of thin oil films induced by quasi-static loading. The method uses a steel-oil-mercury system along with complex impedance analysis, which provides the simultaneous measurement of the film thickness and breakdown ratio. In the case of hexadecane, the relationship between thickness and the breakdown ratio is represented by a single master curve independently of the indentation speed. Every breakdown process of hexadecane traces on the same master curve, and its final point is determined by the indentation load. The breakdown process of hexadecane includes two stages: one is the decrement of the film thickness without breakdown, and the other is the decrement of the film thickness with the drastic progress of breakdown.

View full abstract

Piezoelectric elements, which are electrically connected to external shunt circuits, are introduced to suppress bending vibration of a scale model of a railway vehicle. The authors proposed two types of shunt circuits aiming at practical use. One circuit is equivalent to an inductor and a resistor in series, and the other a negative capacitor and a resistor, and both circuits are designed for use under conditions of large vibration amplitude that causes high voltage generated by the elements. Results of excitation tests show that the first bending mode of the scale model can be suppressed successfully. Moreover, the circuit including the negative capacitor can also reduce vibration associated with higher eigen modes simultaneously with the first mode.

View full abstract

Demands for shaver blade durability are constantly increasing. Current blades are processed with a variety of coatings, and evaluating the resultant sharpness has become important. When whiskers are cut with a shaver, the blades are known to draw out the whiskers while shaving them off. JIS-C9614 (Japanese Industrial Standards Committee) states that a blade is sharp if, when cutting 15 artificial hairs, it can shave 11 or more of them to less than 0.4 mm. However, this method of evaluating the length of drawn and cut hairs requires observation of one hair at a time, and is thus very inconvenient. As a simpler method of evaluating sharpness, we propose a method of measuring the force to pull a whisker into the shaver as it is cut. It was assumed that artificial hairs are pulled when the shaver blade cuts them. We carried out a test to measure the amount of the pulling force when an artificial hair is cut, and confirmed that there was indeed a pulling force when the whisker and the pulling force, and showed that the relationship was proportional. The above result demonstrated that measuring pulling force to determine shaving effectiveness is more convenient than the conventional method of observation.

View full abstract

Magnetic particles form chain-like clusters in the magnetic field. This phenomenon is of interest in two separate fields, one is a development system of the laser printer and another is an electromagnetic manipulation of biological cells. Experiments on the chain formation in air and oil have been performed in the ultra high magnetic field created by a superconducting magnet. It has been clairfied that the chain length first increased and then decreased in accordance with the increase of the magnetic field. The result has been confirmed by a numerical calculation with the Distinct Element Method that included the mechanical contact force between particles and the magnetic force due to the field created by the coil and adjacent magnetized particles. A periodic boundary condition was employed to perform realistic calculation in a reasonable calculation time. The effect of the density and the diameter of particles was investigated experimentally. The effect of the dry friction between particles was also examined by comparing experimental results performed in air and oil. Lastly, it has been discussed that the static stability of the chain was determined by a minimization principle of the potential energy that consists of the gravitational and magnetic potential energy.

View full abstract

The ACROSS (Accurately Controlled Routinely Operated Signal System) is used to detect subtle changes in the physical state of Earth's structure. The signal is sinusoidal elastic waves generated by the rotation of a rotor with eccentric mass set in ACROSS transmitters. In currently working transmitters, since the rotor is supported by rolling contact bearings, bearing losses are so large that the cooling, lubrication management and bearing life become serious problems. To solve these problems, hydrostatic asymmetric journal gas bearings have been proposed to support the eccentric mass rotors. This paper describes the experimental investigation of rotational characteristics of proposed hydrostatic asymmetric journal gas bearings. It is verified that the rotor amplitude in the journal bearings can be zero at a certain rotational frequency by using trial test rig. In order to decrease the gas consumption and increase more safely operation, test of rotational frequency modulation using electro-pneumatic pressure regulator was carried out. In fixed supply pressure condition, rotor amplitude largely changes in accordance with change of rotational frequency. In controlled supply pressure condition, the rotor amplitude decrease under the operation and the gas consumption also largely decreased.

View full abstract

This paper proposes an intelligent start-up schedule optimization system for a thermal power plant. This system consists of a dynamic simulation, a neural network, and an interactive multi-objective programming technique. In this study, a new intelligent optimization method using the neural network and a genetic algorithm to realize a satisficing trade-off method, which is an interactive multi-objective programming technique, has been developed and introduced into this system. The features of this system are as follows. (1) The start-up schedule can be optimized based on multi-objective evaluation and (2) an optimal and flexible start-up schedule can be determined with a reasonable computing time and calculation accuracy through human-computer interactions. The system is applied to a simulation for a combined cycle power plant, and to optimize from among multiple objectives, based on varying daily requirements. The application results show that optimal and flexible start-up schedules can be obtained within a reasonable computing time and with acceptable calculation accuracy.

View full abstract

Capabilities and complexity of manufacturing systems are increasing and striving for an integrated manufacturing environment. Availability of alternative process plans is a key factor for integration of design, process planning and scheduling. This paper describes an algorithm for generation of alternative process plans by extending the existing framework of the process plan networks. A class diagram is introduced for generating process plans and process plan networks from the viewpoint of the integrated process planning and scheduling systems. An incomplete search algorithm is developed for generating and searching the process plan networks. The benefit of this algorithm is that the whole process plan network does not have to be generated before the search algorithm starts. This algorithm is applicable to large and enormous process plan networks and also to search wide areas of the network based on the user requirement. The algorithm can generate alternative process plans and to select a suitable one based on the objective functions.

View full abstract

Herringbone-grooved hydrodynamic bearings are now being applied to hard disk drive (HDD) spindle motors instead of ball bearings for demand for HDDs with larger storage capacities, faster access times, and reduced sizes. A clear understanding of the vibration characteristics of HDD spindle systems supported by hydrodynamic bearings is needed for the industry to achieve significantly better run-out characteristics. Such HDD spindles are well known to exhibit vibration mainly in rocking mode. From these backgrounds, the resonance vibration characteristics of HDD spindle systems with hydrodynamic bearings were investigated focusing on the rocking resonance mode of the spindles in this paper. To express the resonance vibration, a lumped mass model comprising five main components was used for the study. A comparison of the theoretical results with ones obtained experimentally demonstrated its validity, and each effect of springs and dampers connecting the lumped masses to frequency response of the spindle systems was comprehensively discussed.

View full abstract

When we acquire tactile sensation, contact and relative motion are necessary between our bodies and objects. This implies that the tactile sensation is produced by friction phenomena. The present paper describes the sliding test for estimating the tactile sensation associated with cosmetic foundation. When the cosmetic foundation is rubbed with an apparatus that imitates a human finger, two types of time-evolving signals-normal and tangential-are obtained as the source of the tactile information. In the sliding test with the apparatus under the frictional condition of humans acquiring the tactile sensation, frictional vibration is observed in the tangential signals, which should be related to the tactile sensation associated with the cosmetic foundation. When a surface with a grooved pattern that imitates fingerprints is used in the sliding test, two types of frictional vibrations are observed. If an adequate sliding velocity is selected, the slight difference between the four types of commercial cosmetic foundations is discriminable by using the signals of these vibrations.

View full abstract

The prevention of adhesion of aluminum alloy to tungsten carbide has been investigated fro the standpoint of wettability effect of fluids having simple molecular structure. Sliding experiments were conducted using aluminum alloy disks and tungsten carbide balls with supplying the fluids to the contact region. The fluids with hydroxyl functional group (-OH) and with only alkanes (saturated hydrocarbons) were tested. Contact angles of the fluids on the aluminum alloy were measured to estimate the wettability of the fluids. Experimental results showed that the lower the contact angles of the fluids, the higher the wettability of the fluids on the aluminum alloy disk, and these provided the lowered friction coefficients and no adhesion. Adhesions occurred for the fluids with low wettability. No effect of the existences of hydroxyl functional group and longer hydrocarbon chain was found on the wetting, adhesion, and friction phenomena.

View full abstract

In this study, we investigated that interactive contact surfaces were affected by dust and applied normal loads of cantilever such as bristles. In order to study the effect of interactive contact surfaces, spherical particles (dry borosilicate glass sphere, plastic sphere) with curvature radius (R=5 μm, R=10 μm) were glued to artificial stainless cantilevers (spring constant k=576.7 N/m). The experiments were performed on various normal applied loads using an AFM (Atomic force microscope). The results indicate that spheres with a small curvature radius removed dust more effectively than did either of those with a large curvature radius, abraded by using the stainless cantilever, over the wide contact area (50 μmx50 μm). The plastic spheres tend to deform more than do the borosilicate glass spheres under the same applied load and the spheres with a smaller curvature radius tend to deform than do those with a larger curvature radius and the same material properties. Therefore, it had an influence on interactive surface forces. Restructuring dust aggregates by sliding a cantilever, as well as applying loads and contact pressure, forms a new micro contact area, which influences micro surface forces.

View full abstract

The ISO nuts of styles 1 and 2 specified in ISO 898-2 and ISO 898-6 are designed to prevent the thread stripping failure mode based on the calculation method called the Alexander's theory. However, it have been pointed out that the thread stripping sometimes occurs in over-loaded bolt/nut assemblies of certain sizes and property classes due to the inadequate specifications in the relevant International Standards. This paper treats the design concepts on ISO nuts for the revision of the above ISO Standards, which is now taking place. The simulation program has been reproduced based on the Alexander's theory, and the calculated values were compared with the specified ones. The results clearly show that there are both over-designed specifications and insufficiently designed ones with higher risk of stripping. Therefore, the possible ways to exclude such problems have been considered based on the distribution of the bolt/nut thread strength ratio calculated. Finally, it is shown that that the most practical way is to change the hardness range of nut, and the program to obtain the adequate specifications is proposed with verification.

View full abstract

Metal joining by brazing or diffusion bonding is typically performed at temperatures around 1573K. At such temperatures, atmosphere or vacuum furnaces are required to avoid metal oxidation while heating. The drawbacks of atmosphere furnaces are their use of explosive gases such as hydrogen and the inability of using metal conveyor belts above 1423K. In this study, a non-oxidizing continuous furnace that uses only inert gas atmospheres was developed to work in conjunction with a carbon/carbon composite conveyor belt that can be used up to 2873K, and was used in metal joining processes. The development of the furnace, its working principle and features, and its application in brazing and diffusion bonding of stainless steel are reported with supporting experimental data.

View full abstract