Transient analysis of an advanced static var compensator using quad-series voltage-source PAM inverters

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.     

Dyeing properties of oxygen low-temperature plasma-treated wool and nylon 6 fibres with acid and basic dyes

Wool and nylon 6 fibres treated with oxygen low-temperature plasma were dyed with acid and basic dyes. Despite the increase of electronegativity of the fibre surface caused by the plasma treatment, the rate of dyeing of wool was increased with both dyes, while that of nylon 6 was decreased with the acid dye and increased with the basic dye.     

Sensorless control of synchronous reluctance motors using on‐line parameter identification method not affected by position estimation accuracy

This paper presents a novel on‐line parameter identification method for sensorless control of Synchronous Reluctance Motors (SynRMs). Although conventional sensorless control methods based on mathematical models usually need some complex measurements of motor parameters in advance, the proposed identification method does not require them and can be realized on‐line. The proposed method identifies motor parameters under sensorless control, so rotor position and velocity cannot be used to identify these parameters. However, the proposed method does not need rotor position and velocity, and identified parameters are not affected by these estimation errors. The sensorless control using identified motor parameters is realized, and the effectiveness of the proposed method is verified by experimental results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 62–69, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20258     

Combining natural language with direct manipulation: the conceptual framework for a hybrid human-computer interface

This paper describes the development of a conceptual model of an interaction system for future human-computer interaction. It is suggested that an integrated system is the most promising solution for diverse users and tasks. A ' hybrid interaction system' is considered, which tries to efficiently direct manipulation, menu selection, and natural language. The mechanism of the natural language interface module is described in more detail. Finally, the allocation of functionalities for generalized tasks on the conceptual model is considered from the taxonomic approach.     

Nonlinear repetitive control with application to trajectory control of manipulators

In this article, a new control scheme named repetitive control is proposed for a class of nonlinear systems described by x(t) = Ax(t) + Bu(t) + n(x(t)) and y(t) = Cx(t), in which the controlled variables follow periodic reference commands. The stability condition is derived by applying the passivity theorem. We show how to apply the repetitive control scheme to the trajectory control of a manipulator. A simple repetitive control scheme is developed for the trajectory control of a manipulator by using nonlinear compensation and feedbacks of position and velocity signals. Experimental results for a three link manipulator verify that the proposed repetitive control reduces the tracking error to a very low level.     

Biodegradation of glutaraldehyde-tanned human umbilical vein grafts

A retrospective analysis of the long-term behavior of 111 glutaraldehyde-tanned human umbilical vein (HUV) grafts implanted between September 1977 and December 1993 was conducted. A total of 81 patients, with a mean age of 68.7 years, received the grafts and were followed up for between 1 and 131 months. The 5-year primary cumulative patency rate for above-knee femoropopliteal bypass was 83.1%, whereas that of other bypasses was 60.9%. An aneurysm of the graft was defined as a physically apparent localized dilatation, with diffuse ectasia being excluded. There were 11 aneurysms found in 9 grafts, 2 of which arose at the factory-made suture lines. The accumulated incidence of aneurysms had reached 21.9% by the 6th year. One aneurysm compressed the graft and resulted in limb-threatening ischemia and another resulted in frank rupture. Moreover, reinforcement of the mesh could not prevent aneurysm development, the repair of which is mandatory due to the risk of rupture and acute thrombosis. The HUV grafts showed an acceptable patency rate in the above-knee location, but the incidence of aneurysm formation after 5 years was abnormally high. Thus, both the risks and benefits of HUV grafts must be taken into account when considering their clinical application.     

A new porto-systemic bypass technique for hepatopancreatoduodenectomy with portal vein resection

When reconstructing the portal vein (PV) following hepatopancreatoduodenectomy (HPD) with PV resection, a new porto-systemic bypass (PSB) technique can be employed to prevent intestinal vascular congestion. The Whipple procedure is performed in a standard manner, as long a portion of the gastrocolic trunk is preserved for insertion of an antithrombogenic catheter (ATC). After harvesting the left external iliac vein and exposing the right great saphenous vein, the end of the ATC is inserted in the superior mesenteric vein via the gastrocolic trunk in the distal direction and the other end of the ATC is inserted in the greater saphenous vein. PSB is achieved as a result of the venous pressure gradient. By employing this technique, an ATC can be inserted without damaging another mesenteric venous branch and with minimal damage to the endothelium, and the small intestine is not exposed in the operative field until enteric reconstruction is started. This technique is a promising option for PSB during HPD with PV resection.     

A mesenteric liposarcoma with production of granulocyte colony-stimulating factor

A 77-year-old female was admitted to our hospital because of pyrexia and a right retroperitoneal mass. Leukocytosis and other inflammatory findings were noted. Bone-marrow aspiration revealed hypercellularity with no malignant cells. An additional mass was detected sonographically in the pelvis. The serum concentration of granulocyte colony-stimulating factor (G-CSF) was highly elevated (299 pg/ml). The tumors were removed at laparotomy, and the pelvic mass was found to arise from the ileocecal mesentery. Postoperatively, white blood cell count and serum G-CSF concentrations decreased to normal levels. The mesenteric tumor showed weakly positive immunostaining for human G-CSF, and Northern and polymerase chain reaction (PCR) analyses detected CSF and its mRNA in the mesenteric tumor.     

Links between Immune Cells from the Periphery and the Brain in the Pathogenesis of Epilepsy: A Narrative Review

Accumulating evidence has demonstrated that the pathogenesis of epilepsy is linked to neuroinflammation and cerebrovascular dysfunction. Peripheral immune cell invasion into the brain, along with these responses, is implicitly involved in epilepsy. This review explored the current literature on the association between the peripheral and central nervous systems in the pathogenesis of epilepsy, and highlights novel research directions for therapeutic interventions targeting these reactions. Previous experimental and human studies have demonstrated the activation of the innate and adaptive immune responses in the brain. The time required for monocytes (responsible for innate immunity) and T cells (involved in acquired immunity) to invade the central nervous system after a seizure varies. Moreover, the time between the leakage associated with blood–brain barrier (BBB) failure and the infiltration of these cells varies. This suggests that cell infiltration is not merely a secondary disruptive event associated with BBB failure, but also a non-disruptive event facilitated by various mediators produced by the neurovascular unit consisting of neurons, perivascular astrocytes, microglia, pericytes, and endothelial cells. Moreover, genetic manipulation has enabled the differentiation between peripheral monocytes and resident microglia, which was previously considered difficult. Thus, the evidence suggests that peripheral monocytes may contribute to the pathogenesis of seizures.