scholarly journals Design Techniques in Rock and Soil Engineering

2021 ◽  
Author(s):  
Zahid Ur Rehman ◽  
Sajjad Hussain ◽  
Noor Mohammad ◽  
Akhtar Gul ◽  
Bushra Nawaz
Keyword(s):  
Numerical Methods ◽  
Good Practice ◽  
Empirical Methods ◽  
Mathematical Methods ◽  
Closed Form Solutions ◽  
Initial Stage ◽  
Final Design ◽  
Tunnel Design ◽  
The Stability ◽  
Design Techniques

At the initial stage of tunnel design, the tunnel stability can be assessed by different design techniques which are broadly classified into three categories i.e. Mathematical Analysis, Empirical Methods and Numerical Analysis. Mathematical methods or closed form solutions are more precise methods; however, its use is limited to simple geometries and almost impossible for complex geometries due to complex and tedious calculations involved. In practice, Empirical and Numerical Methods are usually used for stability analysis of tunnels. It should be noted that it is not the replacement of final design. Empirical design methods use information about the structural geology and other rock mass properties as input that can be easily obtained at the initial stage of a project. Numerical Methods commonly require mechanical properties, especially strength and deformation of rocks. Numerical methods are also considered as precise due to provision of allowance for variable inputs and geometry and having ability for sensitivity analysis. It is good practice to evaluate the stability of tunnels using at least two Empirical methods and validated through Numerical methods.

scholarly journals New Edible Packaging Material with Function in Shelf Life Extension: Applications for the Meat and Cheese Industries

Foods ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 562
Author(s):  
Roxana Gheorghita (Puscaselu) ◽  
Sonia Amariei ◽  
Liliana Norocel ◽  
Gheorghe Gutt
Keyword(s):  
Food Industry ◽  
Microbial Growth ◽  
Activity Index ◽  
Life Extension ◽  
Total Count ◽  
Initial Stage ◽  
Edible Packaging ◽  
New Material ◽  
The Stability ◽  
General Appearance

Nowadays, biopolymer films have gained notoriety among the packaging materials. Some studies clearly test their effectiveness for certain periods of time, with applicability in the food industry. This research has been carried out in two directions. Firstly, the development and testing of the new edible material: general appearance, thickness, retraction ratio, color, transmittance, microstructure, roughness, and porosity, as well as mechanical and solubility tests. Secondly, testing of the packaged products—slices of cheese and prosciutto—in the new material and their maintenance at refrigeration conditions for 5 months; thus, the peroxide index, color, and water activity index were evaluated for the packaged products. The results emphasize that the packaging is a lipophilic one and does not allow wetting or any changes in the food moisture. The results indicate the stability of the parameters within three months and present the changes occurring within the fourth and fifth months. Microbiological tests indicated an initial microbial growth, both for cheese slices and ham slices. Time testing indicated a small increase in the total count number over the 5-month period: 23 cfu/g were found of fresh slices of prosciutto and 27 cfu/g in the case of the packaged ones; for slices of cheese, the total count of microorganisms indicated 7 cfu/g in the initial stage and 11 cfu/g after 5 months. The results indicate that the film did not facilitate the growth of the existing microorganisms, and highlight the need to purchase food from safe places, especially in the case of raw-dried products that have not undergone heat treatment, which may endanger the health of the consumer. The new material tested represents a promising substitute for commercial and unsustainable plastic packaging.

scholarly journals Implicit difference schemes for quasilinear parabolic functional equations

2012 ◽  
Vol 45 (4) ◽  
Author(s):  
Milena Matusik
Keyword(s):  
Numerical Methods ◽  
Differential Equations ◽  
Functional Differential Equations ◽  
Initial Boundary ◽  
Difference Schemes ◽  
New Class ◽  
Implicit Difference Schemes ◽  
Functional Differential ◽  
The Stability ◽  
Quasilinear Parabolic

AbstractWe present a new class of numerical methods for quasilinear parabolic functional differential equations with initial boundary conditions of the Robin type. The numerical methods are difference schemes which are implicit with respect to time variable. We give a complete convergence analysis for the methods and we show that the new methods are considerable better than the explicit schemes. The proof of the stability is based on a comparison technique with nonlinear estimates of the Perron type for given functions with respect to functional variables. Results obtained in the paper can be applied to differential equations with deviated variables and to differential integral problems.

Parametric Vibration of Viscoelastic Moving Belts Using Standard Linear Solid Model

2001 ◽  
Author(s):  
Zhichao Hou ◽  
Jean W. Zu
Keyword(s):  
Order Approximation ◽  
Dynamic Responses ◽  
Solid Model ◽  
Nontrivial Solutions ◽  
Closed Form Solutions ◽  
Standard Linear Solid Model ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
The Stability ◽  
First Order Approximation

Abstract By using a standard linear solid model to describe the viscoelasticity of the belt material, a vibration analysis of a parametrically excited moving belt is performed. Closed-form solutions at principal resonance and summation resonance are derived at the first order approximation. The existence conditions and stability are discussed for the nontrivial solutions, yielding explicit expressions of the existence and the stability conditions in terms of the detuning parameter. Numerical examples clearly show the effects of tension fluctuations and translating speeds on the amplitudes of dynamic responses, the corresponding existence domains and the stability of the solutions. It is also demonstrated that the stability domains of the nontrivial solutions are different from those corresponding to elastic models.

A Parametric Absorber for Friction-Induced Vibrations

2003 ◽  
Author(s):  
Horst Ecker
Keyword(s):  
Numerical Methods ◽  
Harmonic Function ◽  
Stability Limit ◽  
Conventional System ◽  
Mass System ◽  
Main Mass ◽  
System A ◽  
Excited System ◽  
Excitation Force ◽  
The Stability

This contribution deals with the suppression of friction-induced vibrations of a mechanical system. A two-mass system is considered, with the main mass excited by a friction-generated self-excitation force and a smaller second mass attached to the main mass. The parameter of the connecting stiffness between the main mass and the absorber mass is a harmonic function of time and represents a parametric excitation. The purpose of the second mass is to act as a “parametric absorber” and to cancel vibrations. Critical values for the damping parameters of the conventional system are calculated, where the system operates on the stability limit. Analytical and numerical methods are employed to determine the stability of the parameter-excited system. A study for selected parameters shows within which limits friction-induced vibrations can be suppressed effectively by a parametric absorber.

scholarly journals Revision of Threshold Luminance Levels in Tunnels Aiming to Minimize Energy Consumption at No Cost: Methodology and Case Studies

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1707 ◽  
Author(s):  
Lambros T. Doulos ◽  
Ioannis Sioutis ◽  
Aris Tsangrassoulis ◽  
Laurent Canale ◽  
Kostantinos Faidas
Keyword(s):  
Energy Consumption ◽  
Energy Savings ◽  
Fine Tuning ◽  
Case Scenario ◽  
Control Techniques ◽  
Tuning Method ◽  
Scada System ◽  
Initial Stage ◽  
Tunnel Design ◽  
Lighting Systems

Because of the absence of lighting calculation tools at the initial stage of tunnel design, the lighting systems are usually over-dimensioned, leading to over illumination and increased energy consumption. For this reason, a fine-tuning method for switching lighting stages according to the traffic weighted L20 luminance is proposed at no additional cost. The method was applied in a real –case scenario, where L20 luminance of the access zone at eleven (11) existing tunnels was calculated. The traffic weighted method of CR14380 was used in order to calculate the actual luminance levels for the entrance zone. The new transition zone, which decreases luminance curves, was produced and compared with the existing ones. Thus, a new switching control was proposed and programed for the Supervisory Control and Data Acquisition (SCADA) system of the tunnel. The signals of the corresponding eleven L20 meters for a period of eight days were used and the corresponding annual energy consumptions were calculated using the proposed switching program for each tunnel. The results were compared with a number of scenarios in which the existing lighting system was retrofitted with Lighting Emitting Diodes (LED) luminaires. In these scenarios, the new luminaire arrangement was based not only on the existing luminance demand value for the threshold zone, but also on the newly proposed one with two different control techniques (continuous dimming and 10% step dimming). The fine-tuning method for switching resulted in energy savings between 11% and 54% depending on the tunnel when the scenario of the existing installation at no extra cost was used. Energy savings, when LED luminaires were installed, varied between 57% (for the scenario with existing luminance demand value for the threshold zone and 10% step dimming) and 85% (for the scenario with the new calculated luminance demand and continuous dimming).

scholarly journals Predicting multiple planet stability and habitable zone companions in the TESS era

2019 ◽  
Vol 485 (4) ◽  
pp. 4703-4725 ◽  
Author(s):  
Matthew T Agnew ◽  
Sarah T Maddison ◽  
Jonathan Horner ◽  
Stephen R Kane
Keyword(s):  
Numerical Methods ◽  
Numerical Simulations ◽  
Dynamical Stability ◽  
Habitable Zone ◽  
Stable Orbit ◽  
Predictive Tool ◽  
Resonant Orbits ◽  
Test Particles ◽  
The Stability ◽  
Unique Signature

Abstract We present an approach that is able to both rapidly assess the dynamical stability of multiple planet systems, and determine whether an exoplanet system would be capable of hosting a dynamically stable Earth-mass companion in its habitable zone (HZ). We conduct a suite of numerical simulations using a swarm of massless test particles (TPs) in the vicinity of the orbit of a massive planet, in order to develop a predictive tool which can be used to achieve these desired outcomes. In this work, we outline both the numerical methods we used to develop the tool, and demonstrate its use. We find that the TPs survive in systems either because they are unperturbed due to being so far removed from the massive planet, or due to being trapped in stable mean-motion resonant orbits with the massive planet. The resulting unexcited TP swarm produces a unique signature in (a, e) space that represents the stable regions within the system. We are able to scale and translate this stability signature, and combine several together in order to conservatively assess the dynamical stability of newly discovered multiple planet systems. We also assess the stability of a system’s HZ and determine whether an Earth-mass companion could remain on a stable orbit, without the need for exhaustive numerical simulations.

On the stability of some second order numerical methods for weak approximation of Itô SDEs

2010 ◽  
Vol 57 (1) ◽  
pp. 101-124 ◽  
Author(s):  
Amir Haghighi ◽  
S. Mohammad Hosseini
Keyword(s):  
Numerical Methods ◽  
Second Order ◽  
Weak Approximation ◽  
The Stability
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