Proposals for inhibiting abundant phytoplankton growth at the head of a river reservoir

In a river reservoir, the Ishitegawa Dam Reservoir in Japan, sites of abundant phytoplankton growth were investigated in connection with the water movement in the reservoir from January 1982 to January 1984 by comparing the distributions of chlorophyll a, water temperature, and coliform bacteria (Project A). The results distinguished three types of phytoplankton growth, of which one type, the abundant surface growth at the head of the reservoir, was most frequently observed. This case was considered to be caused by mixing of the surface lake water with the inflowing nutrient-rich river water at the shallow lake-head. Subsequently the effects of dissolved calcium and magnesium on the chlorophyll a and phytoplanktonic particulate phosphorus concentrations at the head of the reservoir were investigated until December 1987 (Project B). A trophic index, named the Ca-Mg index, was found which correlated positively with the chlorophyll a and phytoplanktonic particulate phosphorus concentrations in a logarithmic scale and varied in relation to the changes in the same index of the inflowing river water. Based on the ecological results of these two projects, two proposals are presented for inhibiting abundant phytoplankton growth at the head of a river reservoir. Proposal A: make the head deep and, in addition, create a strong near-bottom underflow of the inflowing river water. Proposal B: make a bypass in order to cut off the inflow of river water in the case of a high Ca-Mg index.     

Boundary element iterative techniques for determining the interface boundary between two Laplace domains—a basic study of impedance plethysmography as an inverse problem

The interface boundary between two domains with different conductivity is to be determined from the impedance measured at the domain surface. This is an inverse problem. Two approaches, influence coefficient approach and boundary integral approach, using a boundary element model are presented. To examine the validity of the approaches, numerical experiments are carried out for a two-dimensional field, and the suitability and limitation of the methods for application to impedance plethysmography are discussed.     

CMOS LSI-based multichip flexible neural stimulation device with embedded bulk Pt electrodes

A CMOS LSI-based flexible neural stimulation device application with new fabrication technologies has been developed. The device was designed for application in retinal prosthesis. The device is based on multichip architecture, which enables the LSI-based stimulation device to be flexible. A fabrication process of arrayed bulk Pt electrodes, and a packaging structure of LSI chips with flip-chip bonding technology have been developed. These features provide the fabricated device with a lifetime of ten days in saline solution     

A method for the evaluation of electromagnetic wave absorption potential using surface temperature change under microwave irradiation

Absorption behavior of electromagnetic wave by spherical H₂O-filled SiO₂ shell microcapsule-dispersed paraffin matrix composites is evaluated using a microwave heating and thermographic system. The composites under microwave irradiation show temperature change at the specimen surface. The temperature rises as an increase of a volume fraction of H₂O and the absorption of electromagnetic wave is strongly correlated with the temperature rise.     

Measurement of isobaric heat capacity of R125

The specific isobaric heat capacity (c_p) was measured for R125 (pentafluoroethane) in the gas phase by using a flow calorimeter. Twelve measurements for R125 were obtained at temperatures from 313 to 333 K and at pressures from 0.8 to 2.4 MPa. Some of them are close to the saturation curve. The expanded uncertainty (k = 2) of the temperature measurements is estimated to be less than 23 mK, and that of the pressure measurements is less than 14 kPa. The expanded uncertainty for c_p is estimated to range from 12 to 22 J kg⁻¹ K⁻¹. Also, the experimental data were compared with available equations of state. From the results, it became clear that these data will be essential to improve available models so as to represent more reliable thermodynamic properties of R125 and refrigerant mixtures with R125 that are used for refrigeration and air conditioning systems.     

Packaging for a 40-channel parallel optical interconnection modulewith an over-25-Gbit/s throughput

NTT is currently working on developing a high-throughput interconnection module that is both compact and cost effective. The technology being developed is called “parallel inter-board optical interconnection technology”, or “ParaBIT”. The ParaBIT module that has been developed is the first step; it is a front-end module with 40 channels, a throughput of over 25 Gbit/s, and a transmission distance of over 100 m along multimode fibers. One major feature of this module is the use of vertical-cavity surface-emitting laser (VCSEL) arrays as very cost-effective light sources. These arrays enable the same packaging structure to be used for both the transmitter and receiver. To achieve super-multichannel performance, high-density multiport bare-fiber (BF) connectors were developed for the module's optical interface. Unlike conventional optical connectors, these BF connectors do not need a ferrule or spring. This ensures physical contact with an excellent insertion loss (less than 0.1 dB per channel). A polymeric optical waveguide film with a 45° mirror for coupling to the VCSEL and photo-diode (PD) arrays by passive optical alignment was also developed. To facilitate coupling between the VCSEL/PD array chips and the waveguide, a packaging technique was developed to align and die bond the optical array chips on a substrate. This technique is called transferred multichip bonding (TMB); it can be used to mount optical array chips on a substrate with a positioning error of only several micrometers. These packaging techniques enabled ultra-parallel interconnections to be achieved in prototype ParaBIT modules     

Regular boundary integral solution with dual and complementary variational formulations applied to two-dimensional Laplace problems

Regular boundary integral elements are employed for the dual and complementary variational formulations of Laplace problems. The problems are defined only on the boundary as usual, but as in the manner of charge simulation method (CSM), the source terms are arranged outside the domain so that the singular integral can be avoided. The Laplace problems are analysed and the usefulness of the formulation is discussed in comparison with direct BEM. The scalar potential and electric displacement vector potential functions are used in the dual and complementary formulations, with which the upper and lower bounds of the system energy or the capacitance can also accurately be evaluated.