检索结果-南通市图书馆

Advances in Technologies of Piezoelectric Pumping with valves

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2016年第3期33卷 260-273页

作者： Zhang Jianhui Wang Ying Fu Jun Yan Kang Li Zhiming Zhao Chunsheng College of Mechanical and Electrical Engineering Guangzhou University Guangzhou 510006 P. R. China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 P. R. China College of Mechanical and Electrical Technology Taizhou Polytechnical Institute Taizhou 225300 P. R. China

Piezoelectric pump faces unprecedented challenges when higher expectation and requirements need to be met in their applications mainly to medical treatment,hygiene and public health,and preventive ***,the piezoelectric pump with valve has the disadvantages of complex structure,high duty cycle of valves,and valve movement lagged behind piezoelectric ceramics *** an attempt to inhibit its shortcomings,some researchers presented novel concepts for structural design of piezoelectric pump with valve,which could become a new research *** them,the investigation into various soft valves,represented by soft structure valves made of rigid materials and soft material valves made of flexible materials,has been fruitful in recent *** integrated design of both material and structure can tackle the problems encountered in the study of piezoelectric pump with valve,thus simplifying the pump structure,reducing the duty-cycle of valves,and improving the lagging of valve *** addition,new inventions of pump structure have sprung up,such as the pumps containing a single-chamber with double-drive,single-chamber with single-drive in series and single-chamber with single-drive in parallel,as well as the mixed-chamber in series and *** surveying the recent progresses made by dominant academia in the development of piezoelectric pump encompassing valve,with a particular emphasis on structure design of both valve and pump body,we also summarize and identify the future research directions.

关键词： piezoelectric pumps valves swing oscillator

Analytical analysis of single-stage pressure relief valves

在线全文

学校读者我要写书评

暂无评论

International Journal of Hydromechatronics 2019年第1期2卷 1-2页

作者： Sven Osterland Jurgen Weber Chair of Fluid-Mechatronic Systems Technische Universität Dresden Helmholzstr. 7a Dresden 01069 Germany

The article presents an explicitly straightforward formulation of the stationary and dynamic behaviour of a pressure relief valve (PRV). This includes an analytical solution for the static p-Q-characteristic, the step and harmonic response and a stability criterion using elementary operations only. It also mathematically proves the intrinsic connection between the gradient of the static p-Q-characteristic and the stability. Thus, the new method offers four main advantages.

关键词： single-stage pressure relief valves pressure relief valve (PRV) static p-Q-characteristic

Posterior Urethral valves without Reflux Associated with Bilateral Renal Cortical Atrophy: Diagnosis and Management

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Pediatrics 2023年第6期13卷 791-797页

作者： Bangoura Kaba Kolie Ouo-Ouo Camara Salematou Hassimiou Bangoura M’mah Aminata Camara Emmanuel Diallo Mohamed Lamine Diallo Fatoumata Binta Diop Mamadou Moustapha Kouyate Moustapha Beimy Pé Pediatrics Department CHU Donka Conakry Guinea Gamal Abdel Nasser University of Conakry Conakry Guinea Institute of Nutrition Conakry Guinea

The objective of this case report was to highlight the characteristics of posterior urethral valves observed in a 3-year-old patient and to describe their management. The case of a 4-year-old patient treated for a posterior urethral valve with bilateral renal cortical atrophy was reviewed. The diagnosis was confirmed by abdominal ultrasound, cystography and abdominal CT. He was referred to Martinique (a tertiary health establishment) for effective support. From the acute situation to the fortuitous discovery, its understanding must be deepened because of the potential immediate symptomatic impact in the form of renal colic which can be associated with sepsis, as well as in the long term on renal function. This observation is intended to help the attending physician to initiate his diagnosis and treatment.

关键词： valves Urethra Posterior

Improving Concrete Containment Structures Associated with Fixed-Cone valves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering（科研） 2011年第5期3卷 445-451页

作者： B. Skyler Buck Michael C. Johnson Zachary B. Sharp 不详

Fixed-Cone valves are often used to dissipate energy and regulate flow at the low level outlet works of dams. Fixed-Cone valves, also known as Howell-Bunger valves, create an expanding conical jet allowing the energy of the water to dissipate over a large area. However, in many applications constructing the large stilling basin necessary for these valves is either not possible or not feasible. In order to reduce the relative size of the stilling basin, hoods or concrete containment structures have been used in conjunction with Fixed-Cone valves. This paper discusses the use of baffles in concrete containment structures in order to dissipate energy in a considerably confined space. It was determined that using baffles, in place of a deflector ring and end sill (Used in traditional containment structures.), significantly improves the function of containment structures by reducing downstream flow velocities and improving flow patterns and stability. This information will be useful to engineers allowing them to minimize scour and erosion associated with concrete containment structures.

关键词： valves Containment Structure Energy Dissipation Concrete Erosion Outlet Works

Management of Posterior Urethral valves about 26 Cases

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Urology 2021年第3期11卷 95-102页

作者： A. S. Ondziel Opara L. I. P. Ondima A. M. Ondongo Atipo C. Boutol Mandavo R. B. Banga Mouss Dimi Nyanga P. P. Avala A. W. S. Odzébé P. A. Bouya Faculty of Health Sciences Marien Ngouabi University Brazzaville Republic of Congo Urology and Andrology Department University Hospital Center Brazzaville Republic of Congo Pediatric Surgery Department University Hospital Center Brazzaville Republic of Congo

Aim: To improve management of the posterior urethral valve (PUV) in children in a hospital environment. Patients and Methods: This was a retrospective descriptive study that covered a sixteen (16) years period, from January 1, 2002 to December 31, 2017, In pediatric surgery and urology departments of our teaching hospital, 26 cases of posterior urethral valve (PUV) were involved. The diagnosis was made by retrograde urethrocystography and micturition, supplemented by ultrasound. Results: During this period, 26 patients (1.7%) had a PUV. The mean age of the patients was 73, 2 months with extremes ranging from 6 to 180 months. Fifteen patients consulted for dysuria, 8 for complete retention of urine. Only one patient had a history of rolling the valves to the benign ones. The main complications found were urinary tract infection in 15 children, urolithiasis in 3 children and renal failure in 2 children. Two children had serum creatinine values of 50 and 58 mg/L. The lamination of the posterior urethral valves was performed in all patients. In our series, we had one death from chronic renal failure in a 6-year-old child with a bilateral mute kidney at IVU. Conclusion: The valve diagnosis of the posterior urethra is made late because the diagnosis is still postnatal.

关键词： valves Posterior Urethra Congenital CHU Brazzaville

DISTRIBUTION OF NPY-IMMUNOREACTIVE NERVE FIBRES IN RAT CARDIAC valves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1992年第11期37卷 954-957页

作者：苏慧慈黄威权毛秦雯 Department of Histology and Embryology Fourth Military Medical University Xi'an 710033 PRC

It was known long ago that the mammalian cardiac valves were innervated by adrenergic and cholinergic nerves. Recently, it has been proved that the cardiac valves contain the substance P-immunoreactive nerve fibres which originate from the heart wall. NPYimmunoreactive nerves are present in large numbers within the heart. The results

关键词： cardiac valves immunohistochemistry neuropeptide Y (NPY)

Management of the valves of the Posterior Urethra in Urology

在线全文

学校读者我要写书评

暂无评论

Open Journal of Urology 2018年第5期8卷 166-170页

作者： Cyril Kamadjou Kimassoum Rimtebaye Divine Eyongeta Annie Kameni Justin Kamga Bertin Njinou Medico-Surgical Center of Urology and Mini Invasive Surgery Douala Cameroon National General Referal Hospital N’Djamena Chad Regional Hospital Limbe Cameroon General Hospital Yaounde Cameroon

Aim: Describe the clinical, radiological and management of patients with posterior urethral valves. Materials and Methods: This was a retrospective descriptive study over a period going from January 2011 to December 2016, reviewing 12 cases of patients treated for valves of the urethra posterior to the medical surgical center of urology in Cameroon at Douala. The variables studied were clinical, paraclinical, therapeutic and evolutionary. Results: In 5 years, we had diagnosed and treated 12 cases of posterior urethral valves, an average of 2.4 per year. The average age of patients was 41.6 months with extrems of 3 and 156 months. The reason for consultation was dominated by urinary tract infections. Urethrocystography and echography were performed in all patients and allowed to objectify a bilateral ureterohydronephrosis, a diverticular bladder in 9 cases and 4 cases of vesico-ureteral reflux, including a grade 4 according to the classification of Cendron, 8 patients suffered from acute urinary failure. Renal scintigraphyrealised on 3 patients had as objective in 1 patient the existence of a disfunctioning kidney. The treatment consisted of an endoscopic incision of the valves (n = 8), a vesicostomy (n = 3) and an iterative urethral dilatation with double J catheter placement (n = 1). The evolution was favorable (n = 7), and 5 cases of death were recorded. Conclusion: The endoscopic incision is the gold-standard of the treatment of the valves of the posterior urethra. The vesicostomy is an alternative in the absence of adequate technical platform. Despite adequate support, the prognosis remains burdened with significant mortality.

关键词： valves of the Urethra Vesicostomy Endoscopic Incision Renal Failure

Optimal Control of Hydraulic Position System Employing High Speed On/Off Solenoid Valve

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2000年第1期12卷 46-48页

作者： LIU Shao-jun ZHU Mei-sheng ZHOU Jun-feng College of Mechanical and Electrical Engineering Central South University of TechnologyChangsha 410083China

A hydraulic position system was designed employing two high speed On/Off solenoid valves with PWM(Pulse width modulation) technique and using LQ(Linear Quadratic) optimization principle. Based on the system, the parts of system can be formulated with equations. According to equations, the mathematical model of the system was established. By simulation, the corresponding LQ optimal controller was designed and the PWM signals were generated. The comparison of the simulation and experiment results show that LQ optimal control method with PWM technique employing high speed On/Off solenoid valve can provide better system performance and a high position precision is obtained.

关键词： high speed On/Off solenoid valves PWM technique LQ optimal control

Horseshoe thrombus in a patient with mechanical prosthetic mitral valve: A case report and review of literature

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2015年第9期3卷 838-842页

作者： Sanjay Mehra Assad Movahed Carlos Espinoza Constantin B Marcu Department of Cardiovascular Sciences East Carolina University

Patients with prosthetic cardiac valves are at high risk for thromboembolic complications and need life long anticoagulation with warfarin, which can be associated with variable dose requirements and fluctuating level of systemic anticoagulation and may predispose to thromboembolic and or hemorrhagic complications. Prosthetic cardiac valve thrombosis is associated with high morbidity and mortality. A high index of suspicion is essential for prompt diagnosis. Transthoracic echocardiography, and if required transesophageal echocardiography are the main diagnostic imaging modalities. Medically stable patients can be managed with thrombolytic therapy and anticoagulation, while some patients may require surgical thrombectomy or valve replacement. We present a case report of a patient with prosthetic mitral valve and an unusually large left atrial thrombus with both thromboembolic and hemorrhagic complications.

关键词： Thrombosis Anticoagulation Thrombolytic therapy Transthoracic echocardiogram Prosthetic valves Transesophageal echocardiogram