A 2D CMOS microfluxgate sensor system for digital detection of weakmagnetic fields

This paper presents a CMOS two-dimensional (2-D) vector magnetic sensor system integrating two planar microfluxgate sensors and the complete electronics for sensor excitation and signal readout. The system is based on an industrial 0.8-μm double-poly, double-metal CMOS technology with ferromagnetic NiFeMo cores added in a simple postprocessing sequence. The fluxgate sensors are embedded in a ΣΔ analog-to-digital converter for a stable and precise digital detection of weak magnetic fields. A cascaded ΣΔ modulator topology is utilized to obtain second-order noise shaping and to suppress pattern noise. Within the range of ±50 μT, the system nonlinearity is less than 1.5 μT. The angular resolution as a 2D vector sensor is less than 4° for a measured magnetic induction of 50 μT. This makes the 2-D microfluxgate magnetometer suitable for use as fully integrated electronic compass     

Supercritical CO2 extraction of biological active compounds from loquat seed

Amygdalin and β-sitosterol from roasted powder and ground unroasted loquat seed were extracted using supercritical CO₂. Loquat seed is the waste of loquat fruit (Eribotrya japonica), that called biwa in Japan. Loquat seed contains some active compounds, such as amygdalin, sterol and β-sitosterol. Amygdalin is used for medical purposes, mainly as drug in cancer. β-Sitosterol is found in health supplement for various physical ailments. In this work, extraction was conducted at pressure of 20, 30 and 45 MPa, temperature of 40, 60 and 80 °C, and CO₂ flow rate of 3 ml/min for 180 min. Roasted powder and ground unroasted loquat seeds were used as materials. Component in extract was analyzed by HPLC carried out on 5C18-MS column at 27 °C for amygdalin, and 35 °C for β-sitosterol using acetonitrile:water (85:15 v/v) as mobile phase. Based on results, a change in temperature and pressure affected the yield of total extract, amygdalin and β-sitosterol recovery. For comparison between extract from roasted powder and ground unroasted loquat seed, total extract and β-sitosterol recovery from roasted powder loquat seed were higher than that from unroasted one. On the other hand, amygdalin recovery from ground unroasted seed was much higher than that from roasted powder. The optimum condition of extract from roasted powder and ground unroasted loquat seed and amygdalin recovery were obtained at 80 °C and 20 MPa.     

Relationship between melt flows based on three-dimensional X-ray transmission in situ observation and spatter reduction by angle of incidence and defocussing distance in high-power laser welding of stainless steel

ABSTRACT

The objective of this research is to reveal relationship between melt flows and spatter reduction by angle of incidence and defocusing distance in partial penetration welding of an SUS304 stainless steel plate using a 6-kW power laser beam. In welding speeds from 50 to 250 mm/s, underfilled weld beads with spatters were obtained at more than 150 mm/s. According to the three-dimensional X-ray transmission in situ observation of melt flows at 150 mm/s in welding speed with tungsten carbide (WC) tracers, the melt flows achieved approximately 2.3 m/s in speed and made convex molten-pool surface behind a keyhole inlet grow higher, resulting in spattering over 0.1 mm in diameter. A 2 mm inner defocusing distance or a 20° angle of advance decreased the number of spatter over 0.1 mm in diameter by half or one-third in comparison with that at focal point and 0°. The X-ray transmission images demonstrate that the appropriate defocusing distance and angle of incidence made the speed of the melt flow decrease and the melt flow behind a keyhole inlet circulate, which led to not only suppressing the convex surface but also improving the frequency that the convex surface went back to the molten pool.     

Right coronary artery dissection and acute infarction due to blunt trauma: report of a case

Coronary artery dissection occurring after a nonpenetrating chest trauma is extremely rare. We describe herein the case of a 43-year-old man who suffered traumatic myocardial infarction after an intimal tear of the right coronary artery had been inflicted by a horse stepping on his back.     

Welding phenomena and in-process monitoring in high-power YAG laser welding of aluminium alloy

Laser welding of aluminium alloys is difficult because of their low laser coupling, easy formation of welding defects, etc. and thus the establishment of in process monitoring technique is expected in various industries to obtain highly reliable laser welds. In this study, therefore, both the reflected laser beam and radiation light from die molten pool were investigated as monitoring signals during YAG laser welding of A5052 and A5182 aluminium alloy to confirm validity and usefulness of these signals for monitoring. At the same time, laser-welding phenomena were observed through a high-speed video camera to better interpret the monitored signals. Two signals were detected by utilizing photo sensors and band pass or cut-off filters coaxially against a laser beam and from the above-back direction. In this paper, experimental setup, and monitoring and observation results were presented. The correlation between monitoring signals and welding phenomena was clarified when the welding defects such as underfilling and through holes were formed.     

A CMOS rotary encoder using magnetic sensor arrays

A new type of small magnetic rotary encoder is presented. The device detects the magnetic field of a permanent magnet attached to the end of the rotating shaft using complementary metal-oxide semiconductor (CMOS) magnetic sensors [magnetic field effect transistor (MAGFET) arrays] set in a square arrangement. The sensor array is integrated onto a CMOS chip along with angle-detection circuits, leading to the realization of a compact, cost-effective rotary encoder. A prototype sensor chip with dimensions of 4.3/spl times/4.3 mm/sup 2/ is shown to provide error as low as 3.5/spl deg/ without offset calibration and 0.36/spl deg/ with offset calibration, based on an angle calculation method with mean square estimation. This result shows that the CMOS rotary encoder can achieve resolution of 10 bits/rotation at the cost of calibration.     

A high-sensitivity CMOS image sensor with gain-adaptive column amplifiers

A high-sensitivity CMOS image sensor using gain-adaptive column amplifiers is presented and tested. The use of high gain for the column amplifier reduces input-referred random noise, and when coupled with a column-based digital noise cancellation technique, also reduces fixed pattern noise. An experimental application of the circuit using 0.25-/spl mu/m CMOS technology with pinned photodiodes gave an rms random noise of 263 /spl mu/V and an rms fixed pattern noise of 50 /spl mu/V.     

Preoperative diagnosis of the thoracic aortic aneurysm by three-dimensional CT angiography

Serial eight patients with thoracic aortic aneurysms were evaluated by a newly developed three-dimensional CT angiography (3D-CT) from December 1992 to January 1993. The patients include 3 aortic dissections, 3 aortic arch aneurysms, one descending aortic aneurysm and one thoracoabdominal aortic aneurysm. The surgical treatment was performed after the evaluation of 3D-CT, and the operative findings were compared to the three-dimensional images reconstructed by 3D-CT in all patients. Three-dimensional displays were achieved using the unique method of data collection of the helical (spiral) scanner with continuous tube rotation and continuous table feed. A intravenous contrast material was used to image the thoracic aorta and major aortic branches with the single-breath-hold technique. Two and three-dimensional images reconstructed by 3D-CT were displayed within 10-20 minutes after the scanning. These three-dimensional images of the aortic lesions could be displayed in any angle we chose. Three-dimensional structures of the thoracic aorta and major aortic branches were clearly visualized and easily recognized by 3D-CT. These images were similar to the intraoperative findings and were quite useful to determine the operative procedure. The successful repair of thoracic aortic aneurysm was achieved in all cases. 3D-CT is a new and attractive modality to assess the vascular system. Although our experience is limited, 3D-CT may be a useful and powerful diagnostic method for the surgical treatment of thoracic aortic aneurysm.     

Elucidation of the effect of welding speed on melt flows in high-brightness and high-power laser welding of stainless steel on basis of three-dimensional X-ray transmission in situ observation

This research was performed with the objective of clarifying the effect of welding speed on melt flows during melt-run welding of SUS304 stainless steel plates with a 6-kW power laser beam on the basis of three-dimensional X-ray transmission in situ observation. As welding speed increased from 25 to 250 mm/s, three kinds of welds characterized by porosity formation and no defects or underfilling due to spatters were produced. The average and the maximum values of measured melt flow velocity were 3 and 10 times higher than the welding speed, respectively. Two kinds of circulation flows at the inlet or the tip of a keyhole were confirmed to control heat transfer in a molten pool. It was found that the circulation flows were so sensitive to the welding speed that bubbles resulting in porosity or spatters were often formed. According to X-ray observation of the formation of spatters with tungsten carbide (WC) tracers, as the melt flow rose along the keyhole wall, the velocity was accelerated from 0.24–0.54 m/s near the keyhole inlet. Consequently, the melt flows made the convex surface behind the keyhole grow higher, resulting in spattering.