The Radius of Influence Myth

Empirical formulas to estimate the radius of influence, such as the Sichardt formula, occasionally appear in studies assessing the environmental impact of groundwater extractions. As they are inconsistent with fundamental hydrogeological principles, the term “radius of influence myth” is used by analogy with the water budget myth. Alternative formulations based on the well-known de Glee and Theis equations are presented, and the contested formula that estimates the radius of influence by balancing pumping and infiltration rate is derived from an asymptotic solution of an analytical model developed by Ernst in 1971. The transient state solution of this model is developed applying the Laplace transform, and it is verified against the finite-difference solution. Examining drawdown and total storage change reveals the relations between the presented one-dimensional radial flow solutions. The assumptions underlying these solutions are discussed in detail to show their limitations and to refute misunderstandings about their applicability. The discussed analytical models and the formulas derived from it to estimate the radius of influence cannot be regarded as substitutes for advanced modeling, although they offer valuable insights on relevant parameter combinations.

Non-axisymmetric Homann stagnation-point flow of unsteady Walter's B nanofluid over a vertical cylindrical disk

Particular non-axisymmetric Homann stagnation point flow of Walter’s B fluid over a vertical cylindrical disk is considered in this work. Important physical aspects of newly transient state problem are described by incorporating the effects of magnetic field and mixed convection. Additionally, the temperature and solute concentration are expressed with new parameters in the form of Brownian motion, thermophoretic force, thermal radiation, and 1st order chemical reaction. Furthermore, the problem is modeled with non-linear PDE’s, and which are further converted into ODE’s along with the proposed geometric conditions. Exploration of new physical impacts are described in the form of velocity, temperature, concentration, and displacement thicknesses by applying numerical scheme. However, the momentum equation subjected to the insufficient boundary conditions converting us to apply perturbation technique to reduce the order of ODE accordingly. It is conducted that displacement thicknesses [Formula: see text] and [Formula: see text] tends to its asymptotic value, as [Formula: see text] On the other hand, the displacement thickness [Formula: see text] is found in reverse trends, for the same escalating values of viscoelastic parameter. The skin friction [Formula: see text] variation against viscoelastic parameter is noticed with uplifting trend when [Formula: see text] and vice versa, for [Formula: see text] Outcomes for the Nusselt and Sherwood numbers and rate of heat and mass transfer have been obtained and discussed for parametric variations of the buoyancy parameter ξ, magnetic parameter M, temperature ratio parameter, Brownian motion parameter [Formula: see text], thermophoresis parameter [Formula: see text] and 1st order chemical reaction Rc. Also, shows relative growth for the momentum and concentration profiles.

Bending and flexural-buckling strength of steel members considering strain-rate-effects at elevated temperatures

PurposeIn this study, the bending strength, flexural buckling strength and collapse temperature of small steel specimens with rectangular cross-sections were examined by steady and transient state tests with various heating and deformation rates.Design/methodology/approachThe engineering stress and strain relationships for Japan industrial standard (JIS) SN400 B mild steels at elevated temperatures were obtained by coupon tests under three strain rates. A bending test using a simple supported small beam specimen was conducted to examine the effects of the deformation rates on the centre deflection under steady-state conditions and the heating rates under transient state conditions. Flexural buckling tests using the same cross-section specimen as that used in the bending test were conducted under steady-state and transient-state conditions.FindingsIt was clarified that the bending strength and collapse temperature are evaluated by the full plastic moment using the effective strength when the strain is equal to 0.01 or 0.02 under fast strain rates (0.03 and 0.07 min–1). In contrast, the flexural buckling strength and collapse temperature are approximately evaluated by the buckling strength using the 0.002 offset yield strength under a slow strain rate (0.003 min–1).Originality/valueRegarding both bending and flexural buckling strengths and collapse temperatures of steel members subjected to fire, the relationships among effects of steel strain rate for coupon test results, heating and deformation rates for the heated steel members were minutely investigated by the steady and transient-state tests at elevated temperatures.

A Review on Optimal Control for the Smart Grid Electrical Substation Enhancing Transition Stability

This paper is a research article for finding the optimal control of smart power substations for improving the network parameters and reliability. The included papers are the most essential and main studies in the field, which propose a different approach to reach the best performance in electrical power systems. The parameters for improvement are the ability for tracking of the reference signal, stabilizing the system, reducing the error in steady state and controlling the behavior in transient state. The research focuses with the reaching a better transient stability considering voltage and frequency dynamic parameters. The optimal model for the control is focused on minimizing energy consumption but maintaining the controllable parameters, exploring some optimization techniques to find the optimal control, with of aim of minimizing the response time, the energy consumption, and maximizing the reliability by means of improving the controller to be more robust.

Post-traumatic amnesia

Post-traumatic amnesia is the transient state of altered brain function that may follow a traumatic brain injury. At a practical level, an individual has emerged from post-traumatic amnesia when he or she is fully orientated and with return of continuous memory. However, the clinical manifestations are often more complex, with numerous cognitive domains commonly affected, as well as behaviour. In the acute setting, post-traumatic amnesia may easily go unrecognised; this is problematic as it has important implications for both immediate management and for longer-term prognosis. We therefore recommend its careful clinical assessment and prospective evaluation using validated tools. Patients in post-traumatic amnesia who have behavioural disturbance can be particularly challenging to manage. Behavioural and environmental measures form the mainstay of its treatment while avoiding pharmacological interventions where possible, as they may worsen agitation. Patients need assessing regularly to determine their need for further rehabilitation and to facilitate safe discharge planning.

DESIGN OF ADAPTIVE FUZZY FRACTIONAL ORDER PID CONTROLLER FOR AUTONOMOUS UNDERWATER VEHICLE (AUV) IN HEADING AND DEPTH ATTITUDES

This paper deals with the design of new self-tuning Fuzzy Fractional Order PID (AFFOPID) controller based on nonlinear MIMO structure for an AUV in order to enhance the performance in both transient state and steady state of traditional PID controller. It is particularly advantageous when the effects of highly nonlinear processes, like high maneuver, parameters variation, have to be controlled in presence of sensor noises and wave disturbances. Aspects of AUV controlling are crucial because of Complexity and highly coupled dynamics, time variety and difficulty in hydrodynamic modeling. In this try, the comprehensive nonlinear model of AUV is derived through kinematics and dynamic equations. The scaling factor of the proposed AFFOPID Controller is adjusted online at different underwater conditions. Combination of adaptive fuzzy methods and PID controllers can enhance solving the uncertainty challenge in the PID parameters and AUV parameter uncertainty. The simulation results show that developed control system is stable, competent and efficient enough to control the AUV in path following with stabilized and controlled speed. Obtained results demonstrate that the proposed controller has good performance and significant robust stability in comparison to traditional tuned PID controllers.

Thermal Fluxes and Solar Energy Storage in a Massive Brick Wall in Natural Conditions

The thermal state of building elements is a combination of steady and transient states. Changes in temperature and energy streams in the wall of the building in the transient state are particularly intense in its outer layer. The factors causing them are solar radiation, ambient temperature and long-wave radiation. Due to the greater variability of these factors during the summer, the importance of the transient state increases at this time. The study analysed heat transfer in three aspects, temperatures in the outer, middle and inner parts of the wall, heat fluxes between these layers and absorption of solar energy, heat transfer coefficient on the wall exterior was also calculated. The analysis is based on temperature measurements at several depths in the wall and measurements of solar radiation. The subject of research is a solid brick wall. The results show that the characteristics of heat flow in winter and summer for the local climate show distinct differences. In the winter, the maximum temperature difference between the external and internal surface of the wall was 10 °C and in summer, 20 °C. In the winter, the negative flux on the internal surface reached 10 W/m2 and on the external 40 W/m2 and was constant throughout the day. The mean heat transfer coefficient on the exterior surface for winter week was 8 W/(mK). A Nusselt and Biot number for dimensionless convection analysis was calculated. The research contributes to the calculation of the variability of heat or cold demand in a daily period and to learn about the processes of energy storage in the wall using sensible heat.