Post-lunch nap as a worksite intervention to promote alertness on the job.

A worksite study was conducted to examine whether a 15-min nap during a post-lunch rest period would affect subsequent alertness, performance, and nocturnal sleep in eight factory workers under a 3-week protocol. Subjects were asked to take the nap at 12:30 h on a reclining chair during the nap week, and to remain awake during the no-nap week. The order of these 2 weeks was counterbalanced between the subjects. During the third, follow-up week, each subject determined whether or not she/he would nap. Alertness on the job and nocturnal sleep were assessed using a sleep diary. Wrist activity was also recorded during sleep at night. Choice reaction time task (RT) was performed at 10:00 and 15:00 h every day of the nap week and every other day of the no-nap and follow-up weeks. Perceived alertness was significantly higher in the afternoon after nap than after no nap at the end of the week. Similar effects were observed during the follow-up week where almost half of the subjects napped. No significant differences between the three weeks were found for RT performance or nocturnal sleep. Workers' attitudes toward the nap were favourable. Although further intervention research is required, our results suggest that post-lunch napping may have the potential to promote daytime alertness at work.     

Tribochemical Surface Reaction and Lubricating Oil Film

A radioactive tracer technique was used to investigate a tribo-chemical surface reaction obtained by a thrust collar type friction Machine. Radioactive dibenzyl disulfide labeled with sulfur-35 was used as an additive. Steel and copper disks were used as friction specimens.

Radioactive copper sulfide on the friction surface was quantitatively measured with a G-M tube, and a kinetical analysis of the reaction was carried out.

The friction coefficient decreased linearly depending on the amount of surface produced on the friction surface. This dependency was accompanied by adsorption of dibenzyl disulfide, which made a more effective lubricating oil film and was enhanced by the sulfide on the friction surface.

The results of kinetical analysis were explained effectively by considering the oil film behavior related to the adsorptive action of the surface sulfide.     

Effects of phenol on the properties of pitch produced thermally from the petroleum vacuum residue

A petroleum vacuum residue was thermally treated at 430 °C, with continuous addition of phenol to either the vapour phase or the liquid phase of the reacting system. Addition of phenol to the vapour phase increased the yield of the cracked oil and the fixed carbon of the residual pitch. When phenol was charged to the liquid phase, the yield of the oil remained unchanged, but the amount of the benzeneinsoluble matter in the pitch decreased, probably owing to the inhibition by phenol of the polymerization-condensation reactions of aromatic compounds. In both additions the cracked oil had a higher boiling point than that produced without phenol. Substitution of phenol with methyl groups increased the extent of cracking and coking properties (Roga Index) of the pitch. The effective order of phenol and its derivatives is: Phenol < m-Cresol < o-Cresol < p-Cresol < 2, 4-Dimethylphenol < 2, 6-Dimethylphenol < 2, 4, 6-Trimethylphenol Polyhydric phenol, e.g. catechol, and naphthol also enhanced the cracking reactivity of the residue.     

Development of a novel system to quantify the spatial–temporal parameters for crutch-assisted quadrupedal gait

Abstract

Patients with gait disorders often use bilateral crutches along with their own two legs. It is a kind of quadrupedalism. Crutch-assisted gait is usually described and evaluated qualitatively. In this study, we developed a system to quantify the spatial and temporal parameters for crutch-assisted quadrupedalism. Our system consists of walkway hardware and our originally developed software. We specifically extended the measurable area to 1200 mm × 4800 mm, large enough to measure crutch gait. Using our system, we could describe crutch gait precisely. Our system has a capability to evaluate differences between patients and changes within a patient.     

Dynamic Behavior of Surface-Adsorbed Molecules Under Boundary Lubrication

Friction under boundary lubrication was measured using a pendulum-type friction machine. Long straight-chain fatty acids with even carbon numbers, amine, and alcohol were used as additives, and n-hexadecane was used as the base oil.

Effect of the temperature, chain length of additives and additive concentration were investigated.

The phenomena obtained under 373 K were as follows:

1) “Transition concentration” wherein a drastic change of friction coefficient appeared were observed.

2) “Transition concentration” of amine or alcohol solutions appeared at higher concentration than that of acid solution.

3) In “high concentration region,” the friction coefficient gradually increased with the decrease of the concentration.

4) Temperature raise caused a high friction coefficient.

5) Friction coefficient gradually decreased with an increase in chain length.

6) “Transition concentration” shifted toward low concentration with an increase in chain length.

7) No chain-matching effect was observed.

These results are explained introducing a new concept of adsorption mechanism, where both mechanical disturbance, i.e. friction, and adsorption-desorption process of molecules are taken into consideration.     

Evaluation of Electric Fracture Properties of Piezoelectric Ceramics Using the Finite Element and Single-Edge Precracked-Beam Methods

Single-edge precracked-beam (SEPB) tests were performed on a commercial lead zirconate titanate (PZT) ceramic. Mechanical loading was applied by the crosshead displacement control of a screw-driven electromechanical test machine. The fracture toughness parameter K _C was determined for various electric fields. A finite element analysis was also done to calculate the total potential energy release rate, mechanical strain energy release rate, and stress intensity factor for three-point flexure piezoceramic specimens with permeable and impermeable cracks under displacement and load control conditions. Numerical investigation and comparison with test data indicate that the energy release rate, upon application of the permeable model, is useful for predicting crack growth in PZT ceramic under electromechanical loading. Based on current findings, we suggest that the energy release rate criteria for the permeable crack are superior to fracture criteria for the impermeable crack.     

Anti-wear and friction reducing additives composed of ortho-phenylene phosphate-amine salts for polyether type base stocks

Lubrication properties of amine salts of diaryl phosphates in polyether type base oils were evaluated by means of the four-ball wear test. The unique cyclic phosphate, ortho-phenylene phosphate, prevented wear and reduced friction when combined with tertiary amines. Adsorptivity, solubility, and corrosivity of the additives were taken into account.     

A computing model for enhancing service quality and increasing profitability of corporations: model evaluation based on two different sources data

In this paper, we introduce and evaluate a computing model for enhancing service quality of consumers and increasing profitability of corporations. We discuss the model prediction of the turning and transition period based on data from two different sources. By applying these real data of some leading manufacturing corporations in Japan we analyze the model accuracy. By using the proposed model, the corporation can increase their profit by enhancing the marketable quality. From the analysis, we conclude that even there are some differences between two sources data, the proposed model give a good approximation and prediction of the turning and transition period of Japanese economy.     

Static and Dynamic Properties of Oil Films Containing Organic Polar Compounds on Metal Surfaces,Using Electric Measurements

Using electric measurements, an oil film of liquid paraffin solutions of some surface active compounds was investigated in static, transitional, and dynamic states.

In the static state, the film strength for mechanical deformation depended on the surface active compound in the oil. The adsorbed molecules in the oil film formed a multilayered film causing a mesomorphic state in the oil film. The oil film thickness in the transitional state was reduced by about 30 percent, in comparison with that in the static state. This reduction depended on which surface active compound was added. The film thickness decreased depending on the sliding velocity when it was below 30 cm/sec. The structure of an oil film below 30 cm/sec sliding velocity was considered to be in a dynamic equilibrium between the destruction or disturbance by a mechanical force and the molecular rearrangement or recovery of the structure.