نتایج جستجو برای: pneumatic servomechanism
تعداد نتایج: 7254 فیلتر نتایج به سال:
OBJECTIVES To compare the effectiveness and safety of ultrasonic and pneumatic lithotripters in the treatment of renal stone disease. MATERIALS AND METHODS A total of 227 consecutive percutaneous nephrolithotomy procedures for renal calculi were performed. In 107 patients ultrasonic lithotriptors were used (group I) and in 83 patients pneumatic lithotriptors were used (group II). In the remai...
Despite emergent progress in many fields of bionics, a functional Bionic Voice prosthesis for laryngectomy patients (larynx amputees) has not yet been achieved, leading to a lifetime of vocal disability for these patients. This study introduces a novel framework of Pneumatic Bionic Voice Prostheses as an electronic adaptation of the Pneumatic Artificial Larynx (PAL) device. The PAL is a non-inv...
BACKGROUND and aims: In this prospective study, we determined the long term clinical course of patients with achalasia who were treated by pneumatic dilation using the Browne-McHardy dilator, and determined whether previously described predictors of outcome remain significant after prolonged follow up. METHODS Between 1981 and 1991, 54 consecutive patients were treated by pneumatic dilation a...
Skeletal pneumaticity is found in the presacral vertebrae of most sauropod dinosaurs, but pneumaticity is much less common in the vertebrae of the tail. We describe previously unrecognized pneumatic fossae in the mid-caudal vertebrae of specimens of Giraffatitan and Apatosaurus. In both taxa, the most distal pneumatic vertebrae are separated from other pneumatic vertebrae by sequences of three ...
PURPOSE To compare efficacy and safety of holmium:YAG laser and pneumatic lithotripter in the management of ureteral stones. MATERIALS AND METHODS One hundred and twelve patients with 1 to 2 cm ureteral calculi were selected for pneumatic or holmium:YAG laser transurethral ureterolithotripsy (56 patients in each group). Ultrasonography and plain abdominal x-ray were performed for all the pati...
Rather severe parametric uncertainties and uncertain nonlinearities exist in the dynamic modeling of a parallel manipulator driven by pneumatic muscles. Those uncertainties not only come from the timevarying friction forces and the static force modeling errors of pneumatic muscles but also from the inherent complex nonlinearities and unknown disturbances of the parallel manipulator. In this pap...
We used inclined lithography to fabricate a pneumatic microvalve for tall microchannels such as those used to convey large cells. The pneumatic microvalve consists of three layers. The upper layer is the actual liquid microchannel, which has a parallelogram-shaped cross section of width 500 μm, height 100 μm, and an acute angle of 53.6◦. The lower layer is a pneumatic microchannel that function...
The non-pneumatic anti-shock garment (NASG) is a first-aid device that reverses hypovolaemic shock and decreases obstetric haemorrhage. It consists of articulated neoprene segments that close tightly with Velcro, shunting blood from the lower body to the core organs, elevating blood pressure and increasing preload and cardiac output. This chapter describes the controversial history of the prede...
This paper describes solutions that can be applied to pneumatic manipulator problems in positioning, both for angle trajectories and for long linear trajectories, used in construction tasks. Optimal positioning of a pneumatic manipulator along angle trajectories with minimum control energy consumption is given. The implementation of the control system is presented. Control algorithms for a long...
The performance characteristics of four 24-inch wheelchair tires are considered; one pneumatic and three airless. Specifically, two new airless polyurethane foam tires (circular and tapered cross-section) were compared to both a molded polyisoprene tire and a rubber pneumatic tire. Rolling resistance, coefficient of static friction, spring rate, tire roll-off, impact absorption, wear resistance...
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