Part decomposition and evaluation based on standard design guidelines for additive manufacturability and assemblability

Flow-induced vibration in heat exchangers has been a key source of concern in the process, power generation and nuclear industry for several decades. Many incidents of failure of heat exchangers due to apparent flow-induced vibration have been reported. Design of tube bundles with loosely supported tubes in baffles for process shell and tube heat exchanger and steam generator needs estimation of energy dissipation mechanisms or damping for a safer and long term operation. Damping has a major influence on the flow induced vibrations and is dependant on a variety of factors such as mechanical properties of the tube material, geometry and number of intermediate supports, the physical properties of shell-side fluid, type of tube motion, tube frequency, shell-side temperature etc. Various damping mechanisms have been identified and quantified such as Friction damping, Viscous damping, Squeeze film damping, Support damping and Two-Phase damping which affect the performance with respect to flow induced vibration design, including standard design guidelines. But generally the effects of the higher operating temperatures on the various damping mechanisms are neglected in the general design procedure. The operating temperatures play significant role on the contribution of various damping mechanisms. The current paper focuses on the thermal aspects of damping mechanisms subjected to single phase cross-flow in process heat exchangers and formulates the design guidelines for safer design based on experimental and empirical formulations. The research results show that he increase in the temperature results in the increase of the damping. Moreover it found that the natural frequency is higher for lower mass flow rate and lower working pressures and lower temperatures.

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Communication architecture based on IoT technology to control and monitor pets feeding

JUCS - Journal of Universal Computer Science ◽

10.3897/jucs.65094 ◽

2021 ◽

Vol 27 (2) ◽

pp. 190-207

Author(s):

Yadira Quiñonez ◽

Carmen Lizarraga ◽

Raquel Aguayo ◽

David Arredondo

Keyword(s):

Mobile Application ◽

Electronic Device ◽

Nutritional Assessment ◽

Design Guidelines ◽

Text Messages ◽

Energy Requirements ◽

Food History ◽

Remote Communication ◽

Standard Design ◽

Daily Energy

Technology is currently a significant benchmark in any application area; science and technology have permitted the invention of tools and devices that simplify daily activities by developing software engineering applications that provide automated solutions. In this sense, this work proposes two architectures that allow communication between the electronic device and the mobile application remotely, using the GSM/GPRS communication services and the Twitter social network. This development aims to control dogs' feeding adequately and healthily, providing the ration of food a dog needs according to the daily energy requirements. A nutritional assessment has also been performed considering different factors such as the size, breed, and weight of the dog to calculate the daily ration of healthy and balanced food according to daily energy requirements. Essentially, the electronic device consists of two parts: on the one hand, the electronic design is formed with an Arduino board, a Sim900 module to send and receive text messages, and the ESP8266 Wi-Fi serial transceiver module, which allows establishing the internet connection to receive the tweet that users post, both modules permit remote communication with the device using the Arduino board. On the other hand, the mobile application developed on Android uses a standard design according to the Google material design guidelines, allowing the owner to feed, schedule the feeding, review the dog's food history, and receive alerts when the food is going to be finished.

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Development of Ideal Hump Geometric Characteristics for Different Vehicle Types “Case Study” Urban Roads in Kafr El-Sheikh City (Egypt)

Advances in Civil Engineering ◽

10.1155/2018/3093594 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Sayed A. Shwaly ◽

Mohamed H. Zakaria ◽

Amal H. Al-Ayaat

Keyword(s):

Field Data ◽

Measurement Data ◽

Geometric Dimension ◽

Design Guidelines ◽

Time Interval ◽

Passenger Cars ◽

Screening Process ◽

The Road ◽

Standard Design ◽

Speed Humps

In Egypt, speed humps are often thought as the best and cheapest tool to reduce vehicles speed and consequently decrease the number of potential accidents. The lack of standards in Egypt led to the installation of a number of speed humps with random dimensions and without good justification. They have become in many cases a source of disturbance and discomfort to drivers and passengers especially when they are poorly designed and located. So, standard design guidelines are disparately required. Three streets from the urban road network of Kafr El-Sheikh city were chosen to collect field data. A total of 51 speed humps were chosen for field data survey. Although there are many design shapes of speed humps, the study focused only on the sinusoidal type. As observed in the field survey, it was found that more than 74% of the observed road humps were of the sinusoidal type. The screening process resulted in only 24 sinusoidal shape speed humps from the 51 speed humps firstly chosen. For speed measurement, data were collected by installing a recording camera beside the road carriageway of each speed hump for an hour time interval. Spot speed for three types of vehicles was measured from the recorded videos for each site by using the logger program software. The operating speeds (V85%) at humps locations have been obtained for different vehicles. Regression analysis models were developed to represent the relationships between the operating speeds (V85%) at humps locations for motorcycles, passenger cars vehicles, and microbuses and three variables, hump length, hump height, and the spacing between successive speed humps. Generally, the results demonstrated that spot speed is significantly influenced by speed hump geometric dimension and the spacing between them. Finally, the developed regression lines can be used easily for setting the geometric dimensions for each proposed hump location.

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Effects of Drained Pre-Loading on the Performance of Shallow Foundations on Overconsolidated Clay

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 2 ◽

10.1115/omae2005-67559 ◽

2005 ◽

Cited By ~ 4

Author(s):

B. M. Lehane ◽

C. Gaudin

Keyword(s):

Bearing Capacity ◽

Carrying Capacity ◽

Design Guidelines ◽

Shallow Foundations ◽

Load Carrying Capacity ◽

Numerical Predictions ◽

Standard Design ◽

Load Carrying ◽

Overconsolidated Clay

This paper presents results from a programme of centrifuge experiments which examined the effects of drained preloading on the stiffness and load carrying capacity of shallow square footings founded on an overconsolidated clay. The increases in stiffness and bearing capacity induced by various levels of preloading are quantified and compared with standard design guidelines and previously published numerical predictions.

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Convex Models of Vehicle Response to Unknown but Bounded Terrain

Journal of Applied Mechanics ◽

10.1115/1.2897193 ◽

1991 ◽

Vol 58 (2) ◽

pp. 354-361 ◽

Cited By ~ 6

Author(s):

Yakov Ben-Haim ◽

Isaac Elishakoff

Keyword(s):

Design Guidelines ◽

Vehicle Design ◽

Maximum Acceleration ◽

Bounded Motion ◽

Vibrational Acceleration ◽

Standard Design ◽

Vehicle Response ◽

Range Of Variation ◽

Uniformly Bounded

This study presents a nonprobabilistic set theoretical approach to analyzing uncertainty in vehicle vibrations arising from motion along imperfectly known terrain. The uncertainty in the substrate is described by a set of allowed substrate profile functions. The analysis of the vehicle response consists in determining the range of variation of performance parameters, as the substrate profile varies over the set of allowed functions. This enables characterization of the uncertain but bounded motion of the vehicle as well as optimization of the vehicle design with respect to uncertainty in the substrate. Maximum acceleration during motion on an imperfectly known surface is determined and related to standard design guidelines for limiting exposure to vibrational acceleration. A method is developed for determining the greatest lower bound of the number of sign changes per second of the vibrational acceleration when moving over an irregular and incompletely specified substrate. Motion along uniformly bounded substrates is studied, as well as traversal of barriers.

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Flexural design of precast, prestressed ultra-high-performance concrete members

PCI Journal ◽

10.15554/pcij65.6-02 ◽

2020 ◽

Vol 65 (6) ◽

pp. 35-61

Author(s):

Chungwook Sim ◽

Maher Tadros ◽

David Gee ◽

Micheal Asaad

Keyword(s):

Prestressed Concrete ◽

High Performance ◽

High Performance Concrete ◽

Limit State ◽

Design Guidelines ◽

Design Tool ◽

Supplementary Cementitious Materials ◽

Ultra High Performance Concrete ◽

Concrete Members ◽

Cylinder Strength

Ultra-high-performance concrete (UHPC) is a special concrete mixture with outstanding mechanical and durability characteristics. It is a mixture of portland cement, supplementary cementitious materials, sand, and high-strength, high-aspect-ratio microfibers. In this paper, the authors propose flexural design guidelines for precast, prestressed concrete members made with concrete mixtures developed by precasters to meet minimum specific characteristics qualifying it to be called PCI-UHPC. Minimum specified cylinder strength is 10 ksi (69 MPa) at prestress release and 18 ksi (124 MPa) at the time the member is placed in service, typically 28 days. Minimum flexural cracking and tensile strengths of 1.5 and 2 ksi (10 and 14 MPa), respectively, according to ASTM C1609 testing specifications are required. In addition, strain-hardening and ductility requirements are specified. Tensile properties are shown to be more important for structural optimization than cylinder strength. Both building and bridge products are considered because the paper is focused on capacity rather than demand. Both service limit state and strength limit state are covered. When the contribution of fibers to capacity should be included and when they may be ignored is shown. It is further shown that the traditional equivalent rectangular stress block in compression can still be used to produce satisfactory results in prestressed concrete members. A spreadsheet workbook is offered online as a design tool. It is valid for multilayers of concrete of different strengths, rows of reinforcing bars of different grades, and prestressing strands. It produces moment-curvature diagrams and flexural capacity at ultimate strain. A fully worked-out example of a 250 ft (76.2 m) span decked I-beam of optimized shape is given.

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