Impacts of the Information-technology Revolution on Japanese Manufacturer-supplier Relationships

'Vertical keiretsu', characterized by suppliers' willingness to make customized investments and their long-term relationships with manufacturers, had been recognized as an important source of strength in Japanese industries. Our model predicts that, in contrast to the recent popular argument, the information-technology revolution can strengthen 'vertical keiretsu'. This is because the efficiency of designing customized parts is significantly enhanced if suppliers undertake a substantial level of IT investments such as the introduction of 3D CAD systems, and the customized nature of such investments could reduce the number of potential suppliers. Our interviews with Japanese manufacturers provide a support to this prediction.Customized investment, Information technology, Japanese firm, Vertical Keiretsu, Subcontracting

Boiling heat transfer during impingement of two or three pipe laminar jets onto moving steel sheet

The impingement of pipe laminar jets is commonly used in run-out-table cooling in hot rolling mills. In this process, a moving hot steel sheet is cooled by pipe laminar array jets. When the spacing between two neighbor jets is small in the sheet width direction, flow interaction of cooling water on the sheet is inevitable, resulting in complex heat transfer phenomena. In the present study, the boiling heat transfer during the impingement of two or three pipe laminar jets onto a moving steel sheet was studied by laboratory-scale experiments. The test coolant was water at room temperature. Water jets were produced from 5-mm-diameter pipe nozzles at a mean velocity of 0.8 m/s. The nozzle spacing between two jet centers was 8, 12, or 16 mm. A 0.3-mm-thick stainless steel sheet with a moving velocity of 1.5 m/s was used as the test substrate. The temperature of steel ranged from 300 to 500°C. The flow was observed by flash photography, and the heat transfer characteristics were studied by an infrared thermography technique. It was found that high heat flux regions were formed near the jet impact points on the moving solid. Flow interaction occurred between two jets, where the heat removal rate was relatively small compared to that in the jet impact regions. The effects of the nozzle spacing, number of nozzles, and temperature of the solid on the boiling heat transfer characteristics were studied in detail from an industrial viewpoint

Boiling Heat Transfer Characteristics of Vertical Water Jet Impinging on Horizontally Moving Hot Plate

This study investigates the heat transfer characteristics of a circular jet pointing upward that impinges on a moving hot steel sheet by using a laboratory-scale setup. The test liquid was water at 17°C, and the volumetric flow rate of the coolant was set to 450, 960, and 1480 mL/min. The test solid was 0.3 mm thick stainless steel (SUS430) with an initial temperature in the range 300–700°C. The moving velocity of the solid was set to 0.5, 1.0, and 1.5 m/s, and its temperature profile was measured by an infrared camera. The results showed that a region of high heat flux appeared in the area impacted by the jet. The heat transfer characteristics relied heavily on the initial temperature of the solid associated with the boiling patterns—namely, nucleate, transition, and film boiling. Along the boundary between the strong nucleate and the transition boiling regimes, the heat flux took peak values. The local minimum values of heat flux obtained between the transition and the film boiling regimes. The initial temperatures of the solid exhibiting these values were influenced by its moving velocity and the jet impact velocity. Moreover, the heat fluxes in the jet impact region for upward-impinging jets were compared with reported data for downward-impinging jets under the condition whereby the jet impact velocity and diameter in the two cases were nearly identical prior to impact. The two sets of results showed very similar trends, although the flow motions of water varied because of the effect of gravit