scholarly journals Determining Functional Reliability of Pyrotechnic Mechanical Devices

AIAA Journal ◽  
10.2514/2.737 ◽  
1999 ◽  
Vol 37 (3) ◽  
pp. 357-363 ◽  
Author(s):  
Laurence J. Bement ◽  
Herbert A. Multhaup
Keyword(s):  
Functional Reliability ◽  
Mechanical Devices

scholarly journals Determining functional reliability of pyrotechnic mechanical devices

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 357-363 ◽  
Author(s):  
Laurence J. Bement ◽  
Herbert A. Multhaup
Keyword(s):  
Functional Reliability ◽  
Mechanical Devices

scholarly journals Determining functional reliability of pyrotechnic mechanical devices

1997 ◽  
Author(s):  
Laurence Bement ◽  
Herbert Multhaup ◽  
Laurence Bement ◽  
Herbert Multhaup
Keyword(s):  
Functional Reliability ◽  
Mechanical Devices

Optimalisasi Pekerjaan Pemindahan Tanah Pada Proyek Embung Begawan Kota Tarakan Dengan Model Antrian

2017 ◽  
Vol 1 (2) ◽  
pp. 75
Author(s):  
Budi Setiawan ◽  
Hermanto Hermanto
Keyword(s):  
Soil Removal ◽  
Production Capacity ◽  
Optimal Time ◽  
Dump Truck ◽  
Queuing Model ◽  
Soil Movement ◽  
Transportation Equipment ◽  
Model Method ◽  
Mechanical Devices ◽  
Time Required

The Embung Bengawan Project in Tarakan City has several jobs requiring heavy equipment including mechanical soil removal activities. Activity of mechanical soil movement is a series in work of loading and transportation equipment. In order to achieve optimal mechanical soil removal targets, it is necessary to know the performance of the machine during the mechanical soil removal process. The optimization of production is the way to obtain production that is in accordance with optimal conditions of mechanical devices. This paper discusses the optimization of dump truck queue time and the number of dump trucks. Performance calculation tool using the method of production capacity of the tool, and calculate the optimal queue using the Queue Model method. Calculation using queuing model method obtained by result of time required by 3 excavator unit and with combined amount of dump truck will give result of cost equal to Rp 48,097,711 / day, and dump truck waiting time in queue to 1 minute. Then the optimal time is obtained by operating 3 units of excavators with a cost difference of Rp 3,572,826 / day from the real condition of the field that operates 2 excavator units

Muscles

2018 ◽  
Author(s):  
Iain A. Anderson ◽  
Benjamin M. O’Brien
Keyword(s):  
Sensory Feedback ◽  
Artificial Muscles ◽  
Combustion Engines ◽  
Electric Motors ◽  
Home Appliances ◽  
Leg Muscles ◽  
Mechanical Devices ◽  
Control Surfaces

Mechanical devices that include home appliances, automobiles, and airplanes are typically driven by electric motors or combustion engines through gearboxes and other linkages. Airplane wings, for example, have hinged control surfaces such as ailerons. Now imagine a wing that has no hinged control surfaces or linkages but that instead bends or warps to assume an appropriate shape, like the wing of a bird. Such a device could be enabled using an electro-active polymer technology based on electronic artificial muscles. Artificial muscles act directly on a structure, like our leg muscles that are attached by tendon to our bones and that through phased contraction enable us to walk. Sensory feedback from our muscles enables proprioceptive control. So, for artificial muscles to be used appropriately we need to pay attention not only to mechanisms for muscle actuation but also to how we can incorporate self-sensing feedback for the control of position.

Machine Plays

2019 ◽  
pp. 385-408
Author(s):  
Hélène Visentin
Keyword(s):  
Seventeenth Century ◽  
Central Europe ◽  
Special Effects ◽  
Royal Power ◽  
Theater Companies ◽  
The Law ◽  
Mechanical Devices ◽  
Public Theater

This article focuses on the practice of machine theater that originated from courtly spectacles in Italy during the Renaissance and developed throughout Western and Central Europe during the seventeenth century. Defined by rapid scene changes and special effects, machine plays reflect the Baroque fascination with both mechanical devices and the law of optics—or scenery perspective—to produce wonder while displaying royal power and prestige. The aim of this article is threefold: to provide an overview of the origins and development of machine theater, to examine the transmission and dissemination of stagecraft knowledge, and to look at the changing nature of machine plays performed by public theater companies, which took advantage of stage machinery innovations to broaden their repertoire, attract a larger audience, and remain competitive.

Prophylaxis of Venous Thromboembolism Following Orthopedic Surgery: Mechanical and Pharmacological Approaches and the Need for Extended Prophylaxis

1999 ◽  
Vol 82 (08) ◽  
pp. 918-924 ◽  
Author(s):  
R.D. Hull ◽  
G.F Pineo
Keyword(s):  
Clinical Trials ◽  
Venous Thromboembolism ◽  
Orthopedic Surgery ◽  
Total Joint Replacement ◽  
Case Series ◽  
Pharmacological Agents ◽  
Thrombotic Disease ◽  
Vein Thrombosis ◽  
Major Orthopedic Surgery ◽  
Mechanical Devices

IntroductionMajor orthopedic surgery, particularly total joint replacement or hip fracture, represents a high risk of future development of postoperative venous thromboembolism and warrants the routine use of prophylaxis with either mechanical devices or pharmacological agents. The aim of prophylaxis is to prevent fatal pulmonary embolism (PE) and the morbidity of deep vein thrombosis (DVT), particularly the development of post-thrombotic syndrome. Patterns of clinical practice, with respect to the prevention of venous thromboembolism and the appropriate use of anticoagulants for the treatment of thrombotic disease, have been strongly influenced by recent consensus conferences.1,2 Rules of evidence for assessing the literature have been applied to all recommendations regarding the prevention and treatment of thrombotic disease. These results were extrapolated using evidence gleaned from major clinical disorders and are based only on nonrandomized clinical trials or case series.1-3 Data from a large number of Level I clinical trials in patients undergoing orthopedic surgery have provided answers to many of the questions regarding prophylaxis of venous thromboembolism. In this review, we will discuss the prevention of venous thromboembolism following orthopedic surgery and discuss some of the controversial issues where further studies are required.

scholarly journals Incidence, Risk, and Visual Outcomes after Repositioning of Acute Non-Traumatic Flap Dislocations Following Femtosecond-Assisted LASIK

2021 ◽  
Vol 10 (11) ◽  
pp. 2478
Author(s):  
Majid Moshirfar ◽  
David G. West ◽  
Chase M Miller ◽  
William B. West ◽  
Shannon E. McCabe ◽  
...  
Keyword(s):  
Risk Factors ◽  
Visual Acuity ◽  
High Myopia ◽  
Case Series ◽  
Retrospective Case ◽  
Visual Outcomes ◽  
Uncorrected Distance Visual Acuity ◽  
Incidence Risk ◽  
Mechanical Devices

Although the use of femtosecond lasers instead of mechanical devices has decreased the incidence of flap complications following laser-assisted in situ keratomileusis (LASIK), dislocations and striae still occur. Flap repositioning is an effective intervention to improve visual outcomes after acute flap complications in both microkeratome-assisted and femtosecond-assisted LASIK. This retrospective case series included patients undergoing flap repositioning secondary to acute flap dislocation and/or visually significant striae within the first two weeks following femtosecond LASIK (FS-LASIK) from 2015 to 2020 at a single institution. Preoperative, intraoperative, and postoperative de-identified data were analyzed for incidence, risk factors, and visual acuity outcomes. The incidence of flap repositioning was 0.35% in 21,536 eyes (n = 70). Indications for repositioning included acute flap dislocation (35.7%) and visually significant striae (64.3%). High myopia (OR = 3.04, p = 0.001) and patient age over 50 years (OR = 3.69, p = 0.001) were the strongest risk factors for these complications. Prior to flap repositioning, uncorrected distance visual acuity (UDVA) of 20/20 or better and 20/40 or better occurred in 19% and 57% of eyes, respectively. After repositioning, a final UDVA of 20/20 or better and 20/40 or better occurred in 78% and 98% of eyes, respectively. After repositioning, one line of UDVA was lost in two eyes (2.8%) and two lines were lost in one eye (1.4%). Risk factors for acute flap dislocation included high myopia and age over 50 years. Flap repositioning was effective in salvaging visual outcomes.

scholarly journals Direct coherent multi-ink printing of fabric supercapacitors

2021 ◽  
Vol 7 (3) ◽  
pp. eabd6978 ◽  
Author(s):  
Jingxin Zhao ◽  
Hongyu Lu ◽  
Yan Zhang ◽  
Shixiong Yu ◽  
Oleksandr I. Malyi ◽  
...  
Keyword(s):  
System Integration ◽  
High Performance ◽  
Mechanical Stability ◽  
Three Dimensional ◽  
High Mass ◽  
Wearable Electronics ◽  
Energy Storage Devices ◽  
Fabrication Procedure ◽  
Self Powered ◽  
Mechanical Devices

Coaxial fiber-shaped supercapacitors with short charge carrier diffusion paths are highly desirable as high-performance energy storage devices for wearable electronics. However, the traditional approaches based on the multistep fabrication processes for constructing the fiber-shaped energy device still encounter persistent restrictions in fabrication procedure, scalability, and mechanical durability. To overcome this critical challenge, an all-in-one coaxial fiber-shaped asymmetric supercapacitor (FASC) device is realized by a direct coherent multi-ink writing three-dimensional printing technology via designing the internal structure of the coaxial needles and regulating the rheological property and the feed rates of the multi-ink. Benefitting from the compact coaxial structure, the FASC device delivers a superior areal energy/power density at a high mass loading, and outstanding mechanical stability. As a conceptual exhibition for system integration, the FASC device is integrated with mechanical units and pressure sensor to realize high-performance self-powered mechanical devices and monitoring systems, respectively.

Artifact Design and Measurement Error Analysis in the Evaluation of Lead Measurement Accuracy of Helical Gear Using Wedge Artifact

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Masaharu Komori ◽  
Fumi Takeoka ◽  
Aizoh Kubo ◽  
Kazuhiko Okamoto ◽  
Sonko Osawa ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Plane Surface ◽  
Design Method ◽  
Measuring Instrument ◽  
Setting Error ◽  
Geometrical Form ◽  
Measurement Experiment ◽  
Mechanical Devices ◽  
Tooth Flank ◽  
Artifact Design

The reduction in the vibration and noise of gears is an important issue in mechanical devices such as vehicles and wind turbines. The characteristics of the vibration and noise of gears are markedly affected by deviations of the tooth flank form of micrometer order; therefore, strict quality control of the tooth flank form is required. The accuracy of the lead measurement for a gear-measuring instrument is usually evaluated using a helicoid artifact. However, it is difficult to manufacture it with high accuracy because the helix is a complicated geometrical form. To solve this problem, a method of evaluating a gear-measuring instrument using a wedge artifact, which includes a highly precise plane surface, has been proposed. In this research, to put the wedge artifact into practice, a design method of the wedge artifact is developed. In addition, the effects of the measuring condition and the setting error of the wedge artifact on the measurement result are investigated. The uncertainty for the evaluation method using a wedge artifact is assessed by a measurement experiment and simulation.

scholarly journals Displacement-based design of precast hinged portal frames with additional dissipating devices at beam-to-column joints

2021 ◽  
Author(s):  
Andrea Belleri ◽  
Simone Labò
Keyword(s):  
Design Methodology ◽  
Linear Time ◽  
Design Procedure ◽  
Time History ◽  
Structural System ◽  
Additional Degree ◽  
Speed Up ◽  
Column Joint ◽  
Displacement Based ◽  
Mechanical Devices

AbstractThe seismic performance of precast portal frames typical of the industrial and commercial sector could be generally improved by providing additional mechanical devices at the beam-to-column joint. Such devices could provide an additional degree of fixity and energy dissipation in a joint generally characterized by a dry hinged connection, adopted to speed-up the construction phase. Another advantage of placing additional devices at the beam-to-column joint is the possibility to act as a fuse, concentrating the seismic damage on few sacrificial and replaceable elements. A procedure to design precast portal frames adopting additional devices is provided herein. The procedure moves from the Displacement-Based Design methodology proposed by M.J.N. Priestley, and it is applicable for both the design of new structures and the retrofit of existing ones. After the derivation of the required analytical formulations, the procedure is applied to select the additional devices for a new and an existing structural system. The validation through non-linear time history analyses allows to highlight the advantages and drawbacks of the considered devices and to prove the effectiveness of the proposed design procedure.

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