Noncontact pulse wave detection by two-band infrared video-based measurement on face without visible lighting

In this paper, we propose a novel noncontact pulse wave monitoring method that is robust to fluctuations in illumination through use of two-band infrared video signals. Because the proposed method uses infrared light for illumination, the method can be used to detect a pulse wave on a human face without visible lighting. The corresponding two-band pixel values in the video signals can be separated into hemoglobin and shading components by application of a separation matrix in logarithmic space for the two pixel values. Because the shading component has been separated, the extracted hemoglobin component is then robust to fluctuations in the illumination. The pixel values in the region of interest were spatially averaged over all the pixels of each frame. These averaged values were then used to form the raw trace signal. Finally, the pulse wave and the corresponding pulse rate were obtained from the raw trace signal through several signal processing stages, including detrending, use of an adaptive bandpass filter, and peak detection. We evaluated the absolute error rate for the pulse rate between the estimated value and the ground truth obtained using an electrocardiogram. In the experiments, we found that the performance of the proposed method was greatly improved compared with that of conventional methods using single-band infrared video.     

A Wide-Dynamic-Range CMOS Image Sensor Based on Multiple Short Exposure-Time Readout With Multiple-Resolution Column-Parallel ADC

A wide-dynamic-range CMOS image sensor based on synthesis of one long and multiple short exposure-time signals is proposed. A high-speed, high-resolution column-parallel integration type analog-to-digital converter (ADC) with a nonlinear slope is crucial for this purpose. A prototype wide-dynamic-range CMOS image sensor that captures one long and three short exposure-time signals has been developed using 0.25-mum 1-poly 4-metal CMOS image sensor technology. The dynamic range of the prototype sensor is expanded by a factor of 121.5, compared with the case of a single long exposure time. The maximum DNL of the ADC is 0.3 least significant bits (LSB) for the single-resolution mode and 0.7 LSB for the multiresolution mode     

Effect of welding speed on microstructural and mechanical properties of laser lap weld joints in dissimilar Al and Cu sheets

Conventional fusion welding of aluminium and copper dissimilar materials is difficult because of poor weldability arising from the formation of brittle intermetallic compounds on the weld zone as well as different chemical, mechanical and thermal properties of welded joints. Joining of Al and Cu plates or sheets offers a metallurgical challenge due to unavoidable formation of brittle intermetallic compounds. Therefore, it is necessary to effectively suppress the formation and growth of Al–Cu intermetallic compounds. For welding of dissimilar Al and Cu sheets, no systematic work has been conducted to reduce these defects. Thus, this paper focuses on the effect of welding speed on the quality of a lap weld joint in the Al and Cu sheets with a single mode fibre laser. It was found that consequently sound strong weld joints could be produced by suppressing the formation of intermetallic compounds in the interface zone at extremely high speeds.     

A High-Speed Low-Noise CMOS Image Sensor With 13-b Column-Parallel Single-Ended Cyclic ADCs

A high-performance CMOS image sensor (CIS) with 13-b column-parallel single-ended cyclic ADCs is presented. The simplified single-ended circuits for the cyclic ADC are squeezed into a 5.6-mum-pitch single-side column. The proposed internal reference generation and return-to-zero digital signal feedback techniques enhance the ADC to have low read noise, a high resolution of 13 b, and a resulting dynamic range of 71 dB. An ultralow vertical fixed pattern noise of 0.1 e_rms ^- is attained by a digital CDS technique, which performs A/D conversion twice in a horizontal scan period (6 mus). The implemented CIS with 0.18-mum technology operates at 390 frames/s and has 7.07-V/lx middots sensitivity, 61- muV/e^- conversion gain, 4.9-e_rms ^- read noise, and less than 0.4 LSB differential nonlinearity.     

Fluxless joining of aluminium alloy to steel by laser irradiation method

A6061 aluminium alloy was joined with steel using Zn filler metal under laser irradiation process. The quality of joint was evaluated by the strength of a lap joint. The effects of laser power irradiation conditions such as travelling speed and defocused distance on the joint strength were investigated. The maximum joint strength was obtained at relatively medium laser travelling speed. The excess reaction between filler metal and aluminium formed thick brittle intermetallic compounds between steel and aluminium alloy. The compounds are considered to lead to the reduction in joint strength. It was found that low wetting at high travelling speed and excess reaction layer formation at low travelling speed were responsible for low joint strength. The study revealed that the relatively high joint strength between aluminium alloy and steel was obtained by laser joining method using Zn filler without the use of flux in air atmosphere.     

Ex vivo evaluation of the NASA/DeBakey axial flow ventricular assist device. Results of a 2 week screening test

The authors investigated the antithombogenicity of the NASA/DeBakey axial flow ventricular assist device in an ex vivo calf model. The device is 3 inches in length and 1 inch in largest diameter. The pump weighs 53 g and displaces 15 ml. The unit consists of three major components: a flow straightener, a spinning inducer/impeller, and a diffuser. The impeller has rod shaped permanent magnets embedded within the six blades and is activated magnetically by a motor stator that is positioned outside the flow tube. Previous 2 day screening tests demonstrated an antithrombogenic configuration in short-term implantation. Based on the results of these 2 day screening tests, five pumps with the best configuration were implanted into a calf for 2 weeks for anti thrombogenicity confirmation. Pumps were implanted paracorporeally, and heparin was used to maintain activated clotting time to approximately 250 sec. Each pump was changed every 2 weeks as planned. During the experiment, all pumps demonstrated stable pumping. The required electric power was 7 to 8 watts and pump flow was maintained at 4 L/min. The calf was in excellent condition. Liver and renal function were maintained, plasma free hemoglobin was kept at less than 4 mg/dl (3.3 +/- 0.3 mg/dl), and lactate dehydrogenase was 1043 +/- 36 units/L. In this experimental series, all five pumps passed the 2 week implantation. Two week ex vivo test results indicated very slight thrombus in the hub areas of some pumps. For the next phase of the implantation study, minor design optimization is necessary to completely eliminate thrombus formation. According to our step by step approach, the in vivo test aiming for long-term implantation is ongoing.