Strength Modeling Report

Strength modeling is a complex and multi-dimensional issue. There are numerous parameters to the problem of characterizing human strength, most notably: (1) position and orientation of body joints; (2) isometric versus dynamic strength; (3) effector force versus joint torque; (4) instantaneous versus steady force; (5) active force versus reactive force; (6) presence or absence of gravity; (7) body somatotype and composition; (8) body (segment) masses; (9) muscle group envolvement; (10) muscle size; (11) fatigue; and (12) practice (training) or familiarity. In surveying the available literature on strength measurement and modeling an attempt was made to examine as many of these parameters as possible. The conclusions reached at this point toward the feasibility of implementing computationally reasonable human strength models. The assessment of accuracy of any model against a specific individual, however, will probably not be possible on any realistic scale. Taken statistically, strength modeling may be an effective tool for general questions of task feasibility and strength requirements

The space station tethered elevator system

The optimized conceptual engineering design of a space station tethered elevator is presented. The elevator is an unmanned mobile structure which operates on a ten kilometer tether spanning the distance between the Space Station and a tethered platform. Elevator capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The potential uses, parameters, and evolution of the spacecraft design are discussed. Engineering development of the tethered elevator is the result of work conducted in the following areas: structural configurations; robotics, drive mechanisms; and power generation and transmission systems. The structural configuration of the elevator is presented. The structure supports, houses, and protects all systems on board the elevator. The implementation of robotics on board the elevator is discussed. Elevator robotics allow for the deployment, retrieval, and manipulation of tethered objects. Robotic manipulators also aid in hooking the elevator on a tether. Critical to the operation of the tethered elevator is the design of its drive mechanisms, which are discussed. Two drivers, located internal to the elevator, propel the vehicle along a tether. These modular components consist of endless toothed belts, shunt-wound motors, regenerative power braking, and computer controlled linear actuators. The designs of self-sufficient power generation and transmission systems are reviewed. Thorough research indicates all components of the elevator will operate under power provided by fuel cells. The fuel cell systems will power the vehicle at seven kilowatts continuously and twelve kilowatts maximally. A set of secondary fuel cells provides redundancy in the unlikely event of a primary system failure. Power storage exists in the form of Nickel-Hydrogen batteries capable of powering the elevator under maximum loads

SHM with DOFS of the TMB L-9 tunnel affected by nearby building construction

Degut a la construcció d´un edifici proper, el túnel de la línia 9 es pot veure afectat en el seu estat de deformació i tensional. Per tal de fer un seguiment continuu durant tot el periode de treballs, es planteja una monitorització de la volta i llossa del túnel amb un sensor de fibra òptica distribuïda, que permetrà obtenir les deformacions al formigó amb una resolució de l´ordre de 1 centímetr

Increasing heavy oil reserves in the Wilmington Oil Field through advanced reservoir characterization and thermal production technologies. Annual report, March 30, 1995--March 31, 1996

The objective of this project is to increase heavy oil reserves in a portion of the Wilmington Oil Field, near Long Beach, California, by implementing advanced reservoir characterization and thermal production technologies. Based on the knowledge and experience gained with this project, these technologies are intended to be extended to other sections of the Wilmington Oil Field, and, through technology transfer, will be available to increase heavy oil reserves in other slope and basin clastic (SBC) reservoirs. The project involves implementing thermal recovery in the southern half of the Fault Block II-A Tar zone. The existing steamflood in Fault Block II-A has been relatively inefficient due to several producibility problems which are common in SBC reservoirs. Inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil, and nonuniform distribution of remaining oil have all contributed to poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated formation sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. A suite of advanced reservoir characterization and thermal production technologies are being applied during the project to improve oil recovery efficiency and reduce operating costs

Qualification of Metallized Optical Fiber Connections for Chip-Level MEMS Packaging

A MEMS-based Safety and Arming (S&A) device is being developed for the next generation of Navy torpedoes. The MEMS-based S&A consists of a high aspect ratio MEMS chip fabricated by deep reactive ion etching (DRIE) of silicon on insulator substrates (SOI). The micro-machined structures, which include environmental sensors, actuators, and optical components, are susceptible to stiction related failures. A robust package is essential to transform the fragile MEMS S&A device into a rugged package capable of reliably functioning throughout the military stockpile to target sequence. To adequately protect the MEMS device from deleterious effects of the external environment, the package must be housed in a hermetic, organic-free package. This dissertation presents the design of, analyzes, and qualifies a die-level fluxless packaging concept. The die-level package consists of a metallized seal ring patterned around the perimeter of the chip, including the fiber groove, sidewalls, and base. The fiber grooves provide a fiber optic interconnect between the microstructure area and the macro-environment. A cap chip, with a matching seal ring, completes the clamshell package. Solder is deposited onto the seal ring and in the grooves at the wafer-level on the device and cap chips. A fluxless, and hence organic-free, soldering process joins and seals the fiber-chip assembly on the chip-level. The conditions that govern fluxless soldering are addressed and tailored for success in the developed design. Surface energy models are used to understand the fluxless soldering conditions and to study the geometric stability of fluid solder joints at the fiber to chip interface. Several techniques for fabrication of the chips and assembly of the packages are investigated. The effects of leak rate of the package seal on the internal package environment are discussed in detail to establish an acceptable leak rate of small volume MEMS packages. The calculations are then furthered to determine the acceptable leak path dimensions to ensure moisture does reach unacceptable levels during the package life. The presented work represents the first reported organic-free (fluxless) die-level package seal with optical fibers that cross the seal boundary

Analiza proizvodnje u tvornici kabela

Rad analizira razne aspekte proizvodnje kabela kao što su proizvodni proces, poslovanje i tržišta te korištenje i implementacija simulacije u tvornici za proizvodnju kabela u svrhu optimiranja iskorištenja strojeva. Deatljno je opisana hrvatska tvornica ELKA d.o.o., uključujući proizvodni program, proizvodne procese i ustroj, prostorni raspored i tehnologiju (strojevi i softver CableBuilder and SAP). Simulacijski model načinjen je korištenjem softvera Siemens Tecnomatix 11 Plant Simulation. Ulazni podaci uključivali su broj narudžbi, godišnje proizvodne količine (u kilometrima i tonama), tehnološka vremena, udaljenosti između strojeva i druge. Izvođenjem simulacije uz variranje broja serija u ovisnosti o broju narudžbi, dobiveni su različiti rezultati. Rezultati su prikazani statističkim dijagramima koji sadrže podatke o proizvedenim količinama, vremenskim opterećenjima strojeva i ukupnim vremenima proizvodnje. Na temelju usporedbe rezultata, a za skraćenje ciklusa proizvodnje i povećanje iskorištenja strojeva, kao prikladna se iskazala tzv. strategija Form Postponement (odgoda otpočinjanja proizvodnih aktivnosti koje ovise o specifičnom zahtjevu kupca). Dio rada posvećen je izračunu potrebnog broja viličara za unutarnji transport

Earthquake Engineering

The book Earthquake Engineering - From Engineering Seismology to Optimal Seismic Design of Engineering Structures contains fifteen chapters written by researchers and experts in the fields of earthquake and structural engineering. This book provides the state-of-the-art on recent progress in the field of seimology, earthquake engineering and structural engineering. The book should be useful to graduate students, researchers and practicing structural engineers. It deals with seismicity, seismic hazard assessment and system oriented emergency response for abrupt earthquake disaster, the nature and the components of strong ground motions and several other interesting topics, such as dam-induced earthquakes, seismic stability of slopes and landslides. The book also tackles the dynamic response of underground pipes to blast loads, the optimal seismic design of RC multi-storey buildings, the finite-element analysis of cable-stayed bridges under strong ground motions and the acute psychiatric trauma intervention due to earthquakes

Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform

Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important. An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed. This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown