Multilayer power printed structures suitable for controlling EMI noises generated in power converters

Electromagnetic interference (EMI) noises generated in power converters are diffused on the surface of conductors. This means influences occur from radiated EMI noises emitted from power transmission lines as well as conducted EMI noises transmitted from them. EMI noises diffusing on the surface of conductors are generally difficult to control using conventional concentrated constant theory. Thus, a new approach based on distributed constant circuit theory is needed in order to control EMI noises. A power converter structure to control EMI noises using multilayer power printed circuit technology is studied in this paper. A structure which can control EMI noises should simultaneously satisfy two conditions, i.e., one to shut down and one to attenuate EMI noises. The structure satisfying these conditions is studied through simulations using the Transmission-Line Modeling Method. The simulations show that the diffusion of EMI noises is controlled by dividing the flow of currents produced by EMI noises into the horizontal and perpendicular directions. That is, the horizontal current flow is controlled inside using the differences in the resistance produced from differences between inner and outer diameter of power transmission lines and the perpendicular current flow can be controlled by properly designing the thickness of the dielectric layer sandwiched between P-and N-power transmission lines with the symmetrical structure. Moreover, it is confirmed by simulations and experiments that the attenuation of EMI noises is affected by the width of the power transmission lines. It is expected that the results obtained in this paper can provide important rules when designing power converters with EMI noise control functions which use the multilayer power printed circuit technology.     

Effects of some calcium-related agents on the protoplast transfection of Lactobacillus casei with phage PL-1 DNA

An audit of the treatment procedures routinely adopted by maxillofacial and oral surgeons for the removal of impacted third molars under general anaesthesia was undertaken in South Africa. Most maxillofacial and oral surgeons agree on the method of bone removal, the prescribing of antibiotics, analgesic agents and mouthwashes, the suturing of the incision wound and the post-operative review of patients. The results were compared to a similar study undertaken by Falcon and Roberts (1992) in the UK. With the exception of the method of bone removal, maxillofacial and oral surgeons in both groups share a similar approach to the treatment procedures adopted in the removal of impacted third molars. Some variability, however, existed in both studies with regard to the use of intra-operative local anaesthetic agents, the administration of peri-operative steroids and the use of non-steroidal anti-inflammatory agents.     

Effect of ibudilast on microcirculation thrombosis in rat inner ear

Arterial wall thickening may be quantitatively assessed by measuring the intima-media thickness (IMT) with high resolution ultrasound. Previous studies have shown a good inter/intraobserver variability of IMT measurements in the common carotid. In this study we evaluated the inter/intraobserver variability of IMT measurements in 10 randomly selected asymptomatic subjects (age 55.4 +/- 6). Two carotids and two femorals were studied in each subject. IMT for each patient was the average of five IMT measurements at the artery bifurcation. Three observers repeated the scanning and the measurements twice with no knowledge of the previous readings. The between observer coefficient of variation (CV) was 8.45%; the intraobserver CV (mean of carotids and femorals) varied from 4.4 to 5.1% for the three observers who measured IMT three times. The mean absolute difference between the first and the third measurement was 0.0738 mm. In conclusion IMT measurement variability is mostly due to differences between observers. The intraobserver variability is very small. IMT measurements at the carotid and femoral bifurcations have a low variability and are a good expression of atherosclerosis as they consider early lesions at the bifurcation level which may not be observed in the common carotid.     

Hybrid Link/Path-Based Design for Translucent Photonic Network Dimensioning

The advancement of ultralong-haul transmission technology has dramatically enhanced the all-optical reaches. However, the actual situations of installed fiber and sites for terrestrial network often prevent implementing a purely transparent network, and thus, opaque reshaping retiming regenerating (3R) regeneration is required to guarantee optical signal reachability. Since 3R regenerators based on optical/electrical/optical conversion tend to dominate the total network costs, an efficient network design method that allocates a minimum number of 3R regenerators to optimum locations is essential to build a cost-effective photonic network. In this paper, we propose such a network-dimensioning method by combining the advantages of link-based and path-based design approaches. It first guarantees optical signal reachability for any possible traffic demand in each segmented linear link. After combining all the links, excessive regenerators are eliminated based on the optical signal quality check with -factor calculation for each wavelength path. A trial design of a large-scale mesh network demonstrated a significant cost savings of more than 30% in comparison with a conventional link-based design. In the trial, the impact of fiber loss coefficient over the total network cost was investigated quantitatively, addressing the importance of such quantitative modeling and analysis.     

Air bubbles in the subclavian or internal jugular veins: a common finding on contrast-enhanced CT

BACKGROUND: Foot complications in diabetes incur huge human and medical costs. There is a high incidence of complicated diabetes mellitus in Far North Queensland, particularly in the indigenous communities. METHODS: An audit of 51 patients admitted to Cairns Base Hospital from July 1992 to December 1994 with diabetic foot complications requiring surgical intervention was performed. RESULTS: The majority of surgical procedures were for serious infections in neuropathic feet precipitated by minor trauma. Surgical procedures included debridement/drainage, minor amputation, major amputation and arterial bypass. Half of the patients required more than one procedure and/or multiple admissions. Average length of stay was 48 days. Indigenous patients were overrepresented in this audited group. CONCLUSIONS: Prevention or minimization of diabetic foot complications can be achieved only through improvement in education and vigilance at all levels of the treatment process from community to hospital. Special attention to the needs of indigenous communities with a high incidence of diabetes must be a feature of any future initiatives.     

A new refining process for iron oxide using iron ore and its application to hard ferrites

Kawasaki Steel Corporation and Kawatetsu Mining Co., Ltd. have developed a new refining process to extract iron oxide from iron ore to meet the increase in demand for iron oxide for high- grade hard ferrites. This article discusses the quality of iron oxides and the characteristics of the hard ferrite magnets produced from them.     

Microstructure development of steel during severe plastic deformation

The microstructure development during plastic deformation was reviewed for iron and steel which were subjected to cold rolling or mechanical milling (MM) treatment, and the change in strengthening mechanism caused by the severe plastic deformation (SPD) was also discussed in terms of ultra grain refinement behavior. The microstructure of cold-rolled iron is characterized by a typical dislocation cell structure, where the strength can be explained by dislocation strengthening. It was confirmed that the increase in dislocation density by cold working is limited at 10¹⁶m⁻², which means the maximum hardness obtained by dislocation strengthening is HV3.7 GPa. However, the iron is abnormally work-hardened over the maximum dislocation strengthening by SPD of MM because of the ultra grain refinement caused by the SPD. In addition, impurity of carbon plays an important role in such grain refinement: the carbon addition leads to the formation of nano-crystallized structure in iron.