scholarly journals Mindlin-Reissner Analytical Model with Curvature for Tunnel Ventilation Shafts Analysis

2021 ◽  
Author(s):  
José Álvarez-Pérez ◽  
Fernando Peña
Keyword(s):  
Correction Factor ◽  
Numerical Models ◽  
Continuous Distribution ◽  
Radius Of Curvature ◽  
Tunnel Ventilation ◽  
New Model ◽  
Shear Correction Factor ◽  
Ventilation Shaft ◽  
Proposed Model ◽  
Thick Shells

The formulation and analytic solution of a new mathematical model with constitutive curvature for analysis of tunnel ventilation shaft wall is proposed. Based on the Mindlin-Reissner theory for thick shells, this model also takes into account the shell constitutive curvature and considers an expression of the shear correction factor variable (αn) in terms of the thickness (h) and the radius of curvature (R). The main advantage of the proposed model is that it has the possibility to analyze thin, medium and thick tunnel ventilation shafts. As a result, two comparisons were made: the first one, between the new model and the Mindlin-Reissner model without constitutive curvature with the shear correction factor (α_n=6/5) as a constant, and the other, between the new model and the tridimensional numerical models (solids and shells) obtained by finite element method for different slenderness ratios (h/R). The limitation of the proposed model is that it is to be formulated for a general linear-elastic and axial-symmetrical state with continuous distribution of the mass.

scholarly journals Mindlin-Reissner Analytical Model with Curvature for Tunnel Ventilation Shafts Analysis

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1096
Author(s):  
José Álvarez-Pérez ◽  
Fernando Peña
Keyword(s):  
Correction Factor ◽  
Numerical Models ◽  
Continuous Distribution ◽  
Radius Of Curvature ◽  
Tunnel Ventilation ◽  
New Model ◽  
Shear Correction Factor ◽  
Ventilation Shaft ◽  
Proposed Model ◽  
Thick Shells

The formulation and analytic solution of a new mathematical model with constitutive curvature for analysis of tunnel ventilation shaft wall is proposed. Based on the Mindlin–Reissner theory for thick shells, this model also takes into account the shell constitutive curvature and considers an expression of the shear correction factor variable (αn) in terms of the thickness (h) and the radius of curvature (R). The main advantage of the proposed model is that it has the possibility to analyze thin, medium and thick tunnel ventilation shafts. As a result, two comparisons were made: the first one, between the new model and the Mindlin–Reissner model without constitutive curvature with the shear correction factor αn=5/6 as a constant, and the other, between the new model and the tridimensional numerical models (solids and shells) obtained by finite element method for different slenderness ratios (h/R). The limitation of the proposed model is that it is to be formulated for a general linear-elastic and axial-symmetrical state with continuous distribution of the mass.

RoRePo: Detecting the role information and relative position information for contexts in multi-turn dialogue generation

2021 ◽  
Vol 40 (5) ◽  
pp. 10003-10015
Author(s):  
Zibang Gan ◽  
Biqing Zeng ◽  
Lianglun Cheng ◽  
Shuai Liu ◽  
Heng Yang ◽  
...  
Keyword(s):  
Relative Position ◽  
Latent Variables ◽  
Role Ambiguity ◽  
Position Information ◽  
New Model ◽  
Proposed Model ◽  
Relevant Context ◽  
Position Representation ◽  
Current Speaker ◽  
Relative Position Information

In multi-turn dialogue generation, dialogue contexts have been shown to have an important influence on the reasoning of the next round of dialogue. A multi-turn dialogue between two people should be able to give a reasonable response according to the relevant context. However, the widely used hierarchical recurrent encoder-decoder model and the latest model that detecting the relevant contexts with self-attention are facing the same problem. Their given response doesn’t match the identity of the current speaker, which we call it role ambiguity. In this paper, we propose a new model, named RoRePo, to tackle this problem by detecting the role information and relative position information. Firstly, as a part of the decoder input, we add a role embedding to identity different speakers. Secondly, we incorporate self-attention mechanism with relative position representation to dialogue context understanding. Besides, the design of our model architecture considers the influence of latent variables in generating more diverse responses. Experimental results of our evaluations on the DailyDialog and DSTC7_AVSD datasets show that our proposed model advances in multi-turn dialogue generation.

Improving the Characteristics of Gear Pumps: Part A — Discharge

2003 ◽  
Author(s):  
Ahmed M. M. El-Bahloul ◽  
Yasser Z. R. Ali
Keyword(s):  
Correction Factor ◽  
Helix Angle ◽  
Tooth Profile ◽  
Radius Of Curvature ◽  
Circular Arc ◽  
Pressure Angle ◽  
Face Width ◽  
Angle Change ◽  
Number Of Teeth ◽  
Gear Pumps

The main objective of this paper is to study the effect of gear geometry on the discharge of gear pumps. We have used gears of circular-arc tooth profile as gear pumps and have compared between these types of gearing and spur, helical gear pumps according to discharge. The chosen module change from 2 to 16 mm, number of teeth change from 8 to 20 teeth, pressure angle change from 10 to 30 deg, face width change from 20 to 120 mm, correction factor change from −1 to 1, helix angle change from 5 to 30 deg, and radii of curvature equal 1.4, 1.5, 2, 2.5, 2.75, and 3m are considered. The authors deduced that the tooth rack profile with radius of curvature equal 2.5, 2.75, 3m for all addendum circular arc tooth and convex-concave tooth profile, and derived equations representing the tooth profile, and calculated the points of intersections between curves of tooth profile. We drive the formulas for the volume of oil between adjacent teeth. Computer program has been prepared to calculate the discharge from the derived formulae with all variables for different types of gear pumps. Curves showing the change of discharge with module, number of teeth, pressure angle, face width, correction factor, helix angle, and radius of curvature are presented. The results show that: 1) The discharge increases with increasing module, number of teeth, positive correction factor, face width and radius of curvature of the tooth. 2) The discharge increases with increasing pressure angle to a certain value and then decreases with increasing pressure angle. 3) The discharge decreases with increasing helix angle. 4) The convex-concave circular-arc gears gives discharge higher than that of alla ddendum circular arc, spur, and helical gear pumps respectively. 5) A curve fitting of the results are done and the following formulae derived for the discharge of involute and circular arc gear pumps respectively: Q=A1bm2z0.895e0.065xe0.0033αe−0.0079βQ=A2bm2z0.91ρ10.669e−0.0047β

A Novel Iterated Function System-Based Model for Coloured Image Encryption

2021 ◽  
Vol 12 (2) ◽  
pp. 1-10
Author(s):  
Amine Rahmani
Keyword(s):  
Image Encryption ◽  
Iterated Function System ◽  
Mathematical Concept ◽  
Logistic Equation ◽  
Encryption Scheme ◽  
Symmetric Encryption ◽  
New Model ◽  
Proposed Model ◽  
Iterated Function ◽  
Chaotic Cryptography

Chaotic cryptography has been a well-studied domain over the last few years. Many works have been done, and the researchers are still getting benefit from this incredible mathematical concept. This paper proposes a new model for coloured image encryption using simple but efficient chaotic equations. The proposed model consists of a symmetric encryption scheme in which it uses the logistic equation to generate secrete keys then an affine recursive transformation to encrypt pixels' values. The experimentations show good results, and theoretic discussion proves the efficiency of the proposed model.

A New Advance in Tunnel Ventilation Design Planning

2017 ◽  
Author(s):  
Mark P. Colino ◽  
Elena B. Rosenstein
Keyword(s):  
Ventilation System ◽  
National Fire Protection Association ◽  
Capital Cost ◽  
Smooth Transition ◽  
Mechanical Equipment ◽  
Tunnel Ventilation ◽  
Tunnel Fire ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Ventilation Fan

The new train signaling, traction power and tunnel ventilation system coordination guidelines enacted in National Fire Protection Association (NFPA) Standard 130 have brought the necessity and cost of tunnel ventilation fan shafts into greater focus. The guidelines were aimed at coordinating the three aforementioned rail systems to control the number of trains that could be between successive ventilation shafts during an emergency — in recognition of the fact that the best protection to both incident and non-incident train passengers and crew is to allow no more than one train in each ventilation zone. Though based in safety, these new NFPA guidelines can substantially expand the capital cost and environmental impact of new rail tunnel projects by adding more ventilation shafts and tunnel fan equipment to the scope of work. In addition, the resulting increase in the required number of ventilation shafts and tunnel fan equipment can hinder existing railroad properties as they seek to either increase their train throughput rates, or reduce their tunnel electrical infrastructure. Fortunately, a new kind of emergency ventilation shaft has been developed to facilitate compliance with the NFPA 130 Standard without the excessive capital cost and far-reaching environmental impacts of a traditional emergency ventilation shaft. This new kind of emergency ventilation shaft is called the Crossflue. The Crossflue is a horizontal passage between parallel rail tunnels with a single ventilation fan-motor unit installation. The Crossflue fan is designed to transfer air/smoke flows from one (occupied, incident) tunnel to another (unoccupied, non-incident) tunnel — thereby protecting the incident tunnel at the expense of the non-incident tunnel. The Crossflue passage has angled construction to allow a smooth transition of airflows both into and out of the adjoining tunnels. In addition to the fan, the Crossflue contains a ventilation damper, sound attenuators, ductwork transitions and flexible connectors within the fan equipment line-up; the functionality of all this mechanical equipment is described in the paper. To preserve underground space and minimize the rock excavation, the Crossflue fan is both remotely-powered and remotely-controlled; the fan is only operated as part of a pre-programmed response to tunnel fire events. The methodology utilized to design the Crossflue was taken from the Subway Environmental Design Handbook (SEDH); the SEDH [1] was specifically developed for rail tunnel ventilation design and is the preeminent reference volume in the industry. In summary, the Crossflue provides a dual benefit of achieving NFPA 130 compliance, while at the same time minimizing the construction, equipment, environmental, and energy costs of a traditional tunnel ventilation shaft.

A Flow Theory Integrated Model of Web IS Success

2011 ◽  
pp. 86-106
Author(s):  
Edward J. Garrity ◽  
Yong Jin Kim ◽  
Joseph B. O’Donnell ◽  
Cheul Rhee ◽  
G. Lawrence Sanders
Keyword(s):  
Success Factors ◽  
Flow Theory ◽  
Integrated Model ◽  
Motivating Factors ◽  
Nomological Network ◽  
Is Success ◽  
New Model ◽  
Proposed Model

This chapter develops a new model of web IS success that takes into account both intrinsic and extrinsic motivating factors. The proposed model begins with the Garrity and Sanders model of technologic acceptance and develops an extended nomological network of success factors that draws on motivation and flow theory.

scholarly journals A Hybrid Grey Prediction Model for Small Oscillation Sequence Based on Information Decomposition

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Meng Zhou ◽  
Bo Zeng ◽  
Wenhao Zhou
Keyword(s):  
Prediction Model ◽  
Small Oscillation ◽  
New Method ◽  
Superior Performance ◽  
Small Data ◽  
Grey Prediction ◽  
New Model ◽  
Grey Prediction Model ◽  
Proposed Model ◽  
Oscillation Characteristic

Grey prediction model has good performance in solving small data problem, and has been widely used in various research fields. However, when the data show oscillation characteristic, the effect of grey prediction model performs poor. To this end, a new method was proposed to solve the problem of modelling small data oscillation sequence with grey prediction model. Based on the idea of information decomposition, the new method employed grey prediction model to capture the trend characteristic of complex system, and ARMA model was applied to describe the random oscillation characteristic of the system. Crops disaster area in China was selected as a case study and the relevant historical eight-year data published by government department were substituted to the proposed model. The modelling results of the new model were compared with those of other traditional mainstream prediction models. The results showed that the new model had evidently superior performance. It indicated that the proposed model will contribute to solve small oscillation problems and have positive significance for improving the applicability of grey prediction model.

Analysis and Validation of Cutting Forces Prediction Models in Micromachining

2006 ◽  
Vol 526 ◽  
pp. 13-18 ◽  
Author(s):  
H. Perez ◽  
Antonio Vizan Idoipe ◽  
J. Perez ◽  
J. Labarga
Keyword(s):  
Experimental Data ◽  
Cutting Force ◽  
Cutting Forces ◽  
Prediction Models ◽  
Precision Machining ◽  
New Model ◽  
Proposed Model ◽  
On Line ◽  
Machine Control ◽  
Good Agreement

Many investigations have been developed related to precision machining with features in the millimetre scale. In this paper different cutting force models for micromilling are analyzed and compared. A new model based on specific cutting force that also considers run-out errors has been developed. The estimated cutting forces obtained with this model had good agreement with the experimental data. Also, the proposed model allows to be implemented within the machine control for the on-line optimization of the micromilling process.

Analysis of a new strategy for emergency ventilation and escape scenario in long railway tunnels in the fire mode

2018 ◽  
Vol 233 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Behtash Hakimzadeh ◽  
Mohammad Reza Talaee
Keyword(s):  
Ventilation System ◽  
Control Panel ◽  
Fire Dynamics ◽  
Railway Tunnel ◽  
Rescue Operation ◽  
Tunnel Ventilation ◽  
Precise Control ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Safe Path

The creation of a safe path for evacuating passengers from a tunnel during fire accidents is an important function of a mechanical ventilation system in tunnels. In this work, the operation of emergency ventilation in the fire mode in a long railway tunnel with push–pull ventilation shafts is analyzed using a fire dynamics simulator. As the passenger trains are lengthy – and so is a tunnel – when trains pass through a tunnel, the position of fire on the train becomes an important parameter for rescuing the passengers through a safe path. The novelty of this study is in the design of emergency ventilation scenarios that consider the position of fire on the train in addition to the tunnel ventilation shafts. For this case study, a lengthy (8 km) urban railway tunnel in Tehran with four rail tracks and eight ventilation shafts is considered for designing emergency ventilation scenarios and control of fire products. The fire source is a passenger train wagon with a 25-MW heat release rate. It is shown that, during the rescue operation of the passengers, the location of fire on the train may lead to reverse the ventilation scenario compared with the traditional ones that use only the tunnel shafts. Also, it is observed that there is a region with 50 m radius around each ventilation shaft, i.e. the absolute exhaust zone, where the ventilation system must be set at the exhaust mode due to the presence of fire, to minimize the spreading of fire products downstream. All the logical scenarios of the tunnel ventilation system are designed and demonstrated to create a critical ventilation velocity in the tunnel, which would help in developing a more precise control panel of the tunnel in the fire mode.

On the Quest for the Best Timoshenko Shear Coefficient

2003 ◽  
Vol 70 (1) ◽  
pp. 154-157 ◽  
Author(s):  
M. B. Rubin
Keyword(s):  
Correction Factor ◽  
Timoshenko Beam ◽  
Theoretical Basis ◽  
Natural Frequencies ◽  
Beam Theory ◽  
Vibrational Frequencies ◽  
Timoshenko Beam Theory ◽  
Cosserat Theory ◽  
Shear Correction Factor ◽  
Shear Coefficient

Classical Timoshenko beam theory includes a shear correction factor κ which is often used to match natural vibrational frequencies of the beam. In this note, a number of static and dynamic examples are considered which provide a theoretical basis for specifying κ=1. Within the context of Cosserat theory, natural frequencies of the beam can be matched by appropriate specification of the director inertia coefficients with κ=1.

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