scholarly journals The Dynamics of Multiple Pair-Wise Collisions in a Chain for Designing Optimal Shock Amplifiers

2009 ◽  
Vol 16 (1) ◽  
pp. 99-116 ◽  
Author(s):  
Bryan Rodgers ◽  
Suresh Goyal ◽  
Gerard Kelly ◽  
Michael Sheehy
Keyword(s):  
Power Law ◽  
Low Cost ◽  
Testing Machine ◽  
Design Guidelines ◽  
Mems Devices ◽  
Shock Testing ◽  
Final Mass ◽  
High Acceleration ◽  
Mass Ratios ◽  
A Chain

The major focus of this work is to examine the dynamics of velocity amplification through pair-wise collisions between multiple masses in a chain, in order to develop useful machines. For instance low-cost machines based on this principle could be used for detailed, very-high acceleration shock-testing of MEMS devices. A theoretical basis for determining the number and mass of intermediate stages in such a velocity amplifier, based on simple rigid body mechanics, is proposed. The influence of mass ratios and the coefficient of restitution on the optimisation of the system is identified and investigated. In particular, two cases are examined: in the first, the velocity of the final mass in the chain (that would have the object under test mounted on it) is maximised by defining the ratio of adjacent masses according to a power law relationship; in the second, the energy transfer efficiency of the system is maximised by choosing the mass ratios such that all masses except the final mass come to rest following impact. Comparisons are drawn between both cases and the results are used in proposing design guidelines for optimal shock amplifiers. It is shown that for most practical systems, a shock amplifier with mass ratios based on a power law relationship is optimal and can easily yield velocity amplifications of a factor 5–8 times. A prototype shock testing machine that was made using above principles is briefly introduced.

scholarly journals Shock Pulse Shaping in a Small-Form Factor Velocity Amplifier

2010 ◽  
Vol 17 (6) ◽  
pp. 787-802 ◽  
Author(s):  
Gerard Kelly ◽  
Jeff Punch ◽  
Suresh Goyal ◽  
Michael Sheehy
Keyword(s):  
Pulse Shaping ◽  
Vertical Axis ◽  
Mechanical Shock ◽  
Practical Applications ◽  
Shock Testing ◽  
Acceleration Signal ◽  
High Acceleration ◽  
Component Assembly ◽  
Small Form Factor ◽  
Shock Pulses

This theme of this paper is the design and characterisation of a velocity amplifier (VAMP) machine for high-acceleration shock testing of micro-scale devices. The VAMP applies multiple sequential impacts to amplify velocity through a system of three progressively smaller masses constrained to move in the vertical axis. Repeatable, controlled, mechanical shock pulses are created through the metal-on-metal impact between pulse shaping test rods, which form part of the penultimate and ultimate masses. The objectives are to investigate the controllable parameters that affect the shock pulses induced on collision, namely; striker and incident test rod material; test rod length; pulse shaping mechanisms; and impact velocity. The optimum VAMP configuration was established as a 60 mm long titanium striker test rod and a 120 mm long titanium incident rod. This configuration exhibited an acceleration magnitude and a primary pulse duration range of 5,800–23,400 g and 28.0–44.0μs respectively. It was illustrated that the acceleration spectral content can be manipulated through control of the test rod material and length. This is critical in the context of practical applications, where it is postulated that the acceleration signal can be controlled to effectively excite specific components in a multi-component assembly affixed to the VAMP incident test rod.

scholarly journals Low-Cost Force Sensors Embedded in Physical Human–Machine Interfaces: Concept, Exemplary Realization on Upper-Body Exoskeleton, and Validation

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 505
Author(s):  
Niclas Hoffmann ◽  
Samet Ersoysal ◽  
Gilbert Prokop ◽  
Matthias Hoefer ◽  
Robert Weidner
Keyword(s):  
Low Cost ◽  
Testing Machine ◽  
Measurement Data ◽  
Upper Body ◽  
Testing Environment ◽  
Physical Support ◽  
Pressure Distributions ◽  
Human Machine Interfaces ◽  
Piezoresistive Pressure Sensor ◽  
Material Testing Machine

In modern times, the collaboration between humans and machines increasingly rises, combining their respective benefits. The direct physical support causes interaction forces in human–machine interfaces, whereas their form determines both the effectiveness and comfort of the collaboration. However, their correct detection requires various sensor characteristics and remains challenging. Thus, this paper presents a developed low-cost sensor pad working with a silicone capsule and a piezoresistive pressure sensor. Its measurement accuracy is validated in both an isolated testing environment and a laboratory study with four test subjects (gender-balanced), and an application integrated in interfaces of an active upper-body exoskeleton. In the material-testing machine, it becomes apparent that the sensor pad generally features the capability of reliably determining normal forces on its surface until a certain threshold. This is also proven in the real application, where the measurement data of three sensor pads spatially embedded in the exoskeletal interface are compared to the data of an installed multi-axis load cell and a high-resolution flexible pressure map. Here, the consideration of three sensor pads potentially enables detection of exoskeletal support on the upper arm as well as “poor” fit conditions such as uneven pressure distributions that recommend immediate system adjustments for ergonomic improvements.

scholarly journals Micro-electro-mechanical systems (MEMS): Technology for the 21st century

2014 ◽  
Vol 68 (5) ◽  
pp. 629-641 ◽  
Author(s):  
Tatjana Djakov ◽  
Ivanka Popovic ◽  
Ljubinka Rajakovic
Keyword(s):  
21St Century ◽  
Low Cost ◽  
Mechanical Systems ◽  
Modern Society ◽  
Global Scale ◽  
Thermal Constant ◽  
Mems Devices ◽  
Micro Electro Mechanical Systems ◽  
Industrial Sectors ◽  
Mems Technology

Micro-electro-mechanical systems (MEMS) are miniturized devices that can sense the environment, process and analyze information, and respond with a variety of mechanical and electrical actuators. MEMS consists of mechanical elements, sensors, actuators, electrical and electronics devices on a common silicon substrate. Micro-electro-mechanical systems are becoming a vital technology for modern society. Some of the advantages of MEMS devices are: very small size, very low power consumption, low cost, easy to integrate into systems or modify, small thermal constant, high resistance to vibration, shock and radiation, batch fabricated in large arrays, improved thermal expansion tolerance. MEMS technology is increasingly penetrating into our lives and improving quality of life, similar to what we experienced in the microelectronics revolution. Commercial opportunities for MEMS are rapidly growing in broad application areas, including biomedical, telecommunication, security, entertainment, aerospace, and more in both the consumer and industrial sectors on a global scale. As a breakthrough technology, MEMS is building synergy between previously unrelated fields such as biology and microelectronics. Many new MEMS and nanotechnology applications will emerge, expanding beyond that which is currently identified or known. MEMS are definitely technology for 21st century.

scholarly journals Towards a Living Lab for Enhanced Thermal Comfort and Air Quality: Analyses of Standard Occupancy, Weather Extremes, and COVID-19 Pandemic

2021 ◽  
Vol 9 ◽  
Author(s):  
Giulia Ulpiani ◽  
Negin Nazarian ◽  
Fuyu Zhang ◽  
Christopher J. Pettit
Keyword(s):  
Environmental Quality ◽  
Low Cost ◽  
Design Guidelines ◽  
Weather Extremes ◽  
Fine Grained ◽  
Occupancy Patterns ◽  
Living Lab ◽  
Spatial Coverage ◽  
Educational Buildings ◽  
Extreme Variability

Maintaining indoor environmental (IEQ) quality is a key priority in educational buildings. However, most studies rely on outdoor measurements or evaluate limited spatial coverage and time periods that focus on standard occupancy and environmental conditions which makes it hard to establish causality and resilience limits. To address this, a fine-grained, low-cost, multi-parameter IOT sensor network was deployed to fully depict the spatial heterogeneity and temporal variability of environmental quality in an educational building in Sydney. The building was particularly selected as it represents a multi-use university facility that relies on passive ventilation strategies, and therefore suitable for establishing a living lab for integrating innovative IoT sensing technologies. IEQ analyses focused on 15 months of measurements, spanning standard occupancy of the building as well as the Black Summer bushfires in 2019, and the COVID-19 lockdown. The role of room characteristics, room use, season, weather extremes, and occupancy levels were disclosed via statistical analysis including mutual information analysis of linear and non-linear correlations and used to generate site-specific re-design guidelines. Overall, we found that 1) passive ventilation systems based on manual interventions are most likely associated with sub-optimum environmental quality and extreme variability linked to occupancy patterns, 2) normally closed environments tend to get very unhealthy under periods of extreme pollution and intermittent/protracted disuse, 3) the elevation and floor level in addition to room use were found to be significant conditional variables in determining heat and pollutants accumulation, presumably due to the synergy between local sources and vertical transport mechanisms. Most IEQ inefficiencies and health threats could be likely mitigated by implementing automated controls and smart logics to maintain adequate cross ventilation, prioritizing building airtightness improvement, and appropriate filtration techniques. This study supports the need for continuous and capillary monitoring of different occupied spaces in educational buildings to compensate for less perceivable threats, identify the room for improvement, and move towards healthy and future-proof learning environments.

Design Guidelines for Doubler Plate Repairs of Ship Structures

2005 ◽  
Author(s):  
Pradeep K. Sensharma ◽  
Malcolm Willis ◽  
Aaron Dinovitzer ◽  
Nat Nappi
Keyword(s):  
Engineering Design ◽  
Low Cost ◽  
Design Guidelines ◽  
Performance Data ◽  
Ship Structures ◽  
Buckling Strength ◽  
Relative Ease ◽  
Fatigue And Fracture ◽  
Fracture Assessment ◽  
Design Guidance

The use of doubler plates or ‘doublers’ has become routine for temporary ship repairs. It is the preferred method for ships’ structural repairs for plate corrosion due to its relative ease and low cost of installation over the more costly permanent welded plate insert repair. A lack of performance data and engineering design guidance are the reasons that repairs with doublers are currently considered only temporary. This objective of this study was to develop a set of guidelines for designing and applying doubler plate repairs to ship structures. The guidelines were established using the following criteria: various stress analyses, buckling strength, corrosion types and rates, weld types, and doubler plate fatigue and fracture assessment. Studying and understanding doubler plate repair performance by comparison to that of the primary hull performance allows critical operational decisions to be made with greater ease and confidence. However, the ultimate goal of this study was to establish the design and limitations on the applications of doubler plate repairs for surface ships.

RF-MEMS Based Oscillators

2012 ◽  
pp. 120-155
Author(s):  
Anis Nurashikin Nordin
Keyword(s):  
Acoustic Wave ◽  
Rf Mems ◽  
Low Cost ◽  
Individual Characteristics ◽  
Bulk Acoustic Wave ◽  
Mems Devices ◽  
Device Structure ◽  
Micro Electro Mechanical Systems ◽  
Wireless Transceiver ◽  
Film Bulk

Today’s high-tech consumer market demand complex, portable personal wireless consumer devices that are low-cost and have small sizes. Creative methods of combining mature integrated circuit (IC) fabrication techniques with innovative radio-frequency micro-electro-mechanical systems (RF-MEMS) devices has given birth to wireless transceiver components, which operate at higher frequencies but are manufactured at the low-cost of standard ICs. Oscillators, RF bandpass filters, and low noise amplifiers are the most critical and important modules of any wireless transceiver. Their individual characteristics determine the overall performance of a transceiver. This chapter illustrates RF-oscillators that utilize MEMS devices such as resonators, varactors, and inductors for frequency generation. Emphasis will be given on state of the art RF-MEMS components such as film bulk acoustic wave, surface acoustic wave, flexural mode resonators, lateral and vertical varactors, and solenoid and planar inductors. The advantages and disadvantages of each device structure are described, with reference to the most recent work published in the field.

Low-Water Stream Crossings: The Iowa Experience

2003 ◽  
Vol 1819 (1) ◽  
pp. 355-361 ◽  
Author(s):  
R. R. Gu ◽  
T. J. McDonald ◽  
R. A. Lohnes
Keyword(s):  
Material Selection ◽  
Low Cost ◽  
Geographic Region ◽  
Design Guidelines ◽  
Warning Signs ◽  
Water Stream ◽  
Safe Alternative ◽  
Low Volume Roads ◽  
State And Local ◽  
Selection Of

Replacement of old, unsafe bridges on low-volume roads is an increasing concern in rural America. Counties and local jurisdictions with inadequate bridges on secondary roads are faced with large capital expenditures for replacement structures or possible road closings. Low-water stream crossings (LWSCs) can provide a low-cost and reasonably safe alternative. Three types of LWSC are unvented fords, vented fords, and low-water bridges. A study was conducted to develop design guidelines for all three types of LWSC. Although the study focused on Iowa, the results are thought to be applicable to a wider geographic region. The salient features of this design process, including site selection, selection of most effective LWSC type, and geometric and material selection design, are described for the three types of structures. Although potential legal liability associated with LWSCs is a concern, the Iowa experience indicates that, with adequate warning signs, accidents and subsequent tort claims may actually be less with LWSCs than with deficient and obsolete bridges. On the basis of this history, it appears that potential liability from the use of prudently designed LWSCs is not a high risk. However, each state and local agency should thoroughly study code and local ordinance restrictions when considering LWSC options.

scholarly journals Avalanches and criticality in self-organized nanoscale networks

2019 ◽  
Vol 5 (11) ◽  
pp. eaaw8438 ◽  
Author(s):  
J. B. Mallinson ◽  
S. Shirai ◽  
S. K. Acharya ◽  
S. K. Bose ◽  
E. Galli ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Power Law ◽  
Low Cost ◽  
Reservoir Computing ◽  
Critical Dynamics ◽  
Computational Approaches ◽  
Self Organized ◽  
Computational Performance ◽  
The Brain ◽  
Regular Arrays

Current efforts to achieve neuromorphic computation are focused on highly organized architectures, such as integrated circuits and regular arrays of memristors, which lack the complex interconnectivity of the brain and so are unable to exhibit brain-like dynamics. New architectures are required, both to emulate the complexity of the brain and to achieve critical dynamics and consequent maximal computational performance. We show here that electrical signals from self-organized networks of nanoparticles exhibit brain-like spatiotemporal correlations and criticality when fabricated at a percolating phase transition. Specifically, the sizes and durations of avalanches of switching events are power law distributed, and the power law exponents satisfy rigorous criteria for criticality. These signals are therefore qualitatively and quantitatively similar to those measured in the cortex. Our self-organized networks provide a low-cost platform for computational approaches that rely on spatiotemporal correlations, such as reservoir computing, and are an important step toward creating neuromorphic device architectures.

Mechanical characterization of materials for bulk forming using a drop weight testing machine

2010 ◽  
Vol 224 (9) ◽  
pp. 1795-1804 ◽  
Author(s):  
C M A Silva ◽  
P A R Rosa ◽  
P A F Martins
Keyword(s):  
Flow Stress ◽  
Mechanical Characterization ◽  
Low Cost ◽  
Testing Machine ◽  
Operating Conditions ◽  
Proportional Loading ◽  
Bulk Forming ◽  
Drop Weight ◽  
Characterization Of Materials

The main limitation of mechanical testing equipments is nowadays centred in the characterization of materials at medium loading rates. This is particularly important in bulk forming because strain rate can easily reach values within the aforesaid range. The aim of this article is twofold: (a) to present the development of a low-cost, flexible drop weight testing equipment that can easily and effectively replicate the kinematic behaviour of presses and hammers and (b) to provide a new level of understanding about the mechanical characterization of materials for bulk forming at medium rates of loading. Special emphasis is placed on the adequacy of test operating conditions to the functional characteristics of the presses and hammers where bulk forming takes place and to its influence on the flow stress. This is needed because non-proportional loading paths during bulk forming are found to have significant influence on material response in terms of flow stress. The quality of the flow curves that were experimentally determined is evaluated through its implementation in a finite-element computer program and assessment is performed by means of axisymmetric upset compression with friction. Results show that mechanical characterization of materials under test operating conditions that are similar to real bulk forming conditions is capable of meeting the increasing demand of accurate and reliable flow stress data for the benefit of those who apply numerical modelling of process design in daily practice.

scholarly journals Development of a Pneumatically Driven Cell for Low Cost Automation

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Antonio Carlos Valdiero ◽  
Ivan Jr. Mantovani ◽  
Andrei Fiegenbaum ◽  
Giovani P. B. Dambroz ◽  
Luiz A. Rasia
Keyword(s):  
State Of The Art ◽  
Low Cost ◽  
Control Logic ◽  
Manufacturing Cell ◽  
Technological Advances ◽  
High Acceleration ◽  
Sequential Logic ◽  
And Performance ◽  
Strategy Design ◽  
Fast Acting

The present work addresses the development of a pneumatically driven manufacturing cell for low cost automation applications. This cell can be used in innovative applications as a low cost alternative to increase production and quality in industry. The state of the art shows that technological advances in computing have made possible a drop in equipment prices, making them more accessible. The aim of this work is to develop automation through a classic methodology for a manufacturing cell to minimize errors and facilitate the sequential logic conception. This experimental prototype has been developed at the UNIJUI with financial support by public organizations and companies. Pneumatic actuator used in bench driven has the following advantages: its maintenance is easy and simple, is of relatively low cost, self-cooling properties, and good power density (power/dimension rate), and is fast acting with high acceleration and installation flexibility. However, there are difficulties of control logic due to the complex systems. The sequential controller strategy design considers the pneumatic system, experimental results, and performance of the proposed control strategy.

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