Development of economical maximum power point tracking system for solar cell

Photovoltaic (PV) power generation system operates under various isolation conditions, which may generate several maximum output power points on the I-V curve of the PV array and raises serious problem on Maximum Power Point Tracking (MPPT) control of the system. This research concerned the design of MPPT for photovoltaic system by using PIC controller. A MPPT unit is developed for the optimum coupling of a Photovoltaic Panel (PVP) to the battery (load)through a controlled Buck type dc-dc converter which has made the difference from the past MPPT techniques and made it cost effective. The system has high-efficiency, lower-cost and low-power consumption. Moreover it permits easy modifications. This system operates at its maximum power generation with increasing the PV output power by as much as 32-36%. This study includes the theoretical aspects and experimental results of the proposed method

Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86–1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91–1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable. Funding: UK Medical Research Council and Health Technology Assessment Programme

Aortoiliac steno-occlusive disease

Trattamento endovascolare della patologia steno-occlusiva sorto-iliac

Design of fuzzy based controller for modern elevator group with floor priority constraints

The elevator technologies are developed to serve the requested passenger’s floors with high consideration of passengers’ satisfaction and elevator optimal performance. Responding to the issue, this paper focuses on development of an elevator group controller based on fuzzy algorithm. By introducing a fuzzy controller in an elevator system, this project is developed to manage the required passenger traffic density keeping passenger waiting times within reasonable limits. To increase the performance of the elevator group three major linguistic variables are introduced within a set of fuzzy rules. These include the average waiting time (AWT), power consumption (PC), and floor traffic (FT). When the passenger traffic is high, the low fuzzy control values reduce the importance of priority of floors rather the estimated arrival time is to be minimized. The simulation was accomplished to check the priority of fuzzy system graphically while the actual prototype of elevator system is programmed by PIC device as a controller. As a result a set of fuzzy rules was drawn based on practical considerations; mainly minimization of waiting time and energy consumption. When a few hall requests are registered, the elevator controller will decide which one of the elevators will serve which of the incoming hall requests. In order to manifest the work with actual elevator service, a computer simulation of a four-cars-elevator controller in a twenty storied building is accomplished by using MATLABTM fuzzy logic toolbox and implements the prototype experimental model

Endovascular treatment options for complex abdominal aortic aneurysms

Purpose To report short-term and midterm outcomes of endovascular aneurysm repair (EVAR) of complex aneurysms requiring revascularization of visceral arteries. Materials and Methods Prospective data were collected from patients deemed unsuitable for conventional EVAR and conventional surgery who were treated with different endovascular approaches according to the clinical presentation of the aneurysm. Custom-made fenestrated endovascular aneurysm repair (CM f-EVAR) was used in the elective setting, homemade fenestrated endovascular aneurysm repair (HM f-EVAR) or HM f-EVAR combined with chimney endovascular aneurysm repair (ch-EVAR) was used in the emergent setting in patients with hemodynamic stability, and ch-EVAR was used in unstable cases. The study included 34 consecutive patients. Primary outcomes measured were perioperative mortality and morbidity, renal function impairment (RFI), target vessel patency, and survival at mean follow-up. Results In the CM f-EVAR group (7 of 34 patients; 20.6%), an intraoperative type III endoleak (1 of 7 patients; 14%) sealed spontaneously. At 8.9 months of follow-up, 1 (1 of 7 patients; 14%) death and 1 (1 of 7 patients; 14%) episode of transient RFI were documented. Visceral vessel patency rate was 95.2%. In the HM f-EVAR group (4 of 34 patients; 11.7%) and the combination of HM f-EVAR and ch-EVAR group (3 of 34 patients; 8.8%), no complications were observed at 17.3 months of follow-up. In the ch-EVAR group (20 of 34 patients; 58.8%), visceral patency was 95% at 30.9 months of follow-up. Two cases of transient RFI and 2 cases of permanent RFI were registered (2 of 20 patients; 10%). One asymptomatic renal artery branch occlusion was observed at 11 months of follow-up. No endoleaks were documented. Conclusions Endovascular aneurysm repair techniques including CM f-EVAR, HM f-EVAR or HM f-EVAR in combination with ch-EVAR, and ch-EVAR are valid tools to maintain blood flow in visceral arteries during treatment of complex aortic aneurysms. The proposed interventional protocol based on clinical presentation was feasible in all cases

Aortic aneurysm endovascular treatment with the parallel graft technique from the aortic arch to the iliac axis

BACKGROUND: The chimney technique has been developed for the treatment of complex aortic aneurysms. We analyzed the midterm to long-term outcomes of this approach from a single-center experience.METHODS: From October 2008 to July 2016, 58 patients underwent endovascular aortic aneurysm repair using the chimney technique. Indications for treatment were thoracic aortic aneurysm (TAA) (N.=11), thoracoabdominal aortic aneurysm (TAAA) (N.=2), pararenal aortic aneurysm (PAAA) (N.=15), aortoiliac/isolated hypogastric artery aneurysm (N.=25), type I endoleak after previous TEVAR/EVAR (N.=4), proximal pseudoaneurysm after AAA open repair (N.=1). Elective (82.8%) and emergent (17.2%) procedures were included.RESULTS: The immediate technical success was 100%. Single, double and triple chimneys were performed in 46, 10, and two patients, respectively. Overall, 61 target vessels (three left common carotid arteries, eight left subclavian arteries, three celiac trunks, three superior mesenteric arteries, 19 renal arteries and 25 hypogastric arteries) were involved. Postoperative mortality was 0. No neurologic complications were registered. Primary patency rate of the chimney stent/stent graft was 98.3%. Low-flow type I endoleak was observed in four patients (6.9%). Postoperative chimney graft re-intervention rate was 1.7%. The median follow-up was 32 +/- 20 months (range 3-96 months). Overall estimated survival at 12, 50, and 80 months was 100%, 89% and 44%, respectively. Estimated freedom from endoleak at 1, 12, 24, and 36 months was 96.5%, 95%, 95%, and 93%, respectively. One hypogastric artery stent-graft occluded at the 3rd month of follow-up. No reintervention was performed.CONLUSIONS: Our experience with the chimney technique for aortic aneurysms from the aortic arch to the iliac axis shows promising and durable mid- and long-term results. Endograft oversizing, associated with the chimney graft diameter and length choice remain fundamental to reduce the risk of the most frequent procedure complications: type I endoleak and CG occlusion. The wider use of this technique should be justified in patients considered at high risk for open repair and/or not suitable for the custom-made branched/fenestrated endografts