Search results for "flow [Keywords]"
showing 10 items of 469 documents
Fabric attractors in general triclinic flow systems and their application to high strain shear zones: A dynamical system approach
2007
High strain zones may deform by flow with a triclinic symmetry. This paper describes triclinic flow in a reference frame where Instantaneous Stretching Axes (ISA) are fixed. The operation of triclinic flow is described in two ways: first in terms of flow and the nature of flow eigenvectors and in the second part of the paper in terms of finite strain. In monoclinic flow, at least one of the eigenvectors of the flow coincides with one of the ISA and one or two of the eigenvectors act as attractors of foliation or lineation elements. In triclinic flow some flow eigenvectors are undefined since the two largest eigenvalues (controlling the flow) are imaginary. Imaginary eigenvalues are particul…
Numerical analysis of a new cross-flow type hydraulic turbine for high head and low flow rate
2021
Cross-flow turbines have recently been proposed for energy recovery in aqueducts when the outlet pressure is greater than zero, owing to their constructive simplicity and good efficiency within a large range of flow rates and head drops. In the case of high head drop (higher than 150 m) and relatively small discharge (lower than 0.2 m3/s), the traditional design of these turbines leads to very small widths of the nozzle and the runner; as a consequence, friction losses grow dramatically and efficiency drops down to very low values. Standard Pelton turbines require zero outlet pressure and cannot be used as alternatives. A new counter-pressure hydraulic turbine for high head and low flow rat…
A novel pressure regulation system based on Banki hydro turbine for energy recovery under in-range and out-range discharge conditions
2021
Abstract Efficiency improvement of water distribution networks needs to be in place to guarantee a long life period under suitable operating conditions. Excessive pressure is among the well-known issues encountered in water distribution networks which can cause strength damages to the piping system. In order to overcome this drawback and to reach a suitable water pressure delivery, the present work suggests a novel pressure regulation system. This regulation system is consisting of a Banki turbine equipped with a mobile flap as a control device. The suggested pressure regulation system was experimentally and numerically investigated under in-range i.e. like actual water distribution network…
LV Measurement Device Placement for Load Flow Analysis in MV Smart Grids
2016
This paper deals with the issue of measurement device placement for load flow analysis in medium-voltage (MV) distribution networks. The study is carried out using an innovative measurement algorithm for load flow analysis developed by the authors. It is based on low-voltage (LV) load power measurements applied on a backward/forward algorithm for the load flow resolution. The final aim is to identify the most suitable number and placement of the LV measurement points in order to limit the uncertainty on the power flow estimation to a target value. The proposed approach is based on the uncertainty evaluation of the estimated power flows; a sensitivity analysis is performed in order to assess…
A simplified approach for load flow analysis in MV smart grids based on LV power measurements
2017
This paper presents a simplified approach for load flow analysis in medium voltage (MV) distribution networks. It is a power summation Backward/Forward (B/F) algorithm, based on measurements of active and reactive powers at low voltage (LV) side of MV/LV distribution substations. The proposed solution allows achieving good accuracy, computational efficiency and fast convergence. In order to verify the algorithm performances, simulation studies are carried out in the case of a real test system, i.e. the distribution grid of Favignana Island (Mediterranean Sea, Italy). The compatibility between simulations results and power measurements at the MV bus bars of the generating substation shows th…
Numerical Modelling of Room Thermal Comfort Conditions
2006
Particular heat transfer coefficients of building elements gives quantitative notion only about heat losses through this building element. Analysis of the overall heat balance and heat losses of complete building and study of particular contribution of building elements in overall balance allows one to figure out the state of the building and find the building elements of bounding construction with most significant heat losses. Project variants of the buildings (or rebuilding in case of renovation), which ensure the desirable economy of energy and proportions of investments can be find varying the proportions of the surface area of building elements (e.g., windows and doors). A lot of facto…
Workflow-Based Decision Support for Failure Mode and Effects Analysis
2010
Abstract To achieve high quality designs, processes, and services that meet or exceed industry standards, it is crucial to identify all potential failures throughout a system and work to minimize or prevent their occurrence or effects. This paper presents an innovative approach to Failure Mode and Effects Analysis (FMEA) that uses a Decision Support System (DSS) for supporting the FMEA processes. The DSS is powered by a workflow engine that guides the users through the processes by considering standard work templates or previous similar cases. It is also built as a framework for decision support tools so, beside its default one, different FMEA work instruments can be plugged-in and used thr…
Capacity and safety analysis of hard-shoulder running (HSR). A motorway case study
2016
Abstract Operational motorway conditions can be improved by introducing traffic flow management and control systems, such as ramp metering (RM), high occupancy vehicle (HOV) lanes, real-time variable speed limits (VSLs), reversible lanes (RL), automated highway systems (AHS) and hard-shoulder running (HSR). The effects of such devices need to be examined in terms of capacity and safety. This paper examines the case study of the Italian motorway A22, which is supposed to be equipped with an HSR system implemented along 128 km in order to reduce congestion with consequent improvement in levels of service (LOS). We studied the traffic processes (capacity, flow distribution between lanes, relia…
An Innovative Measurement Approach for Load Flow Analysis in MV Smart Grids
2016
This paper proposes a novel measurement procedure for load flow analysis in medium voltage (MV) smart grids. The new approach is based on power measurements at low voltage (LV) side of MV/LV distribution substations. Such measurements are carried out by means of power quality analyzers. If compared with the load flow methods based on measurements at the MV side, the proposed approach has a lower cost and it offers an equally reliable measurement system. The proposed algorithm takes the basic concept of the current summation backward/forward method; some modifications are introduced to use LV load powers measurements. To this aim, the MV/LV power transformer is properly modeled and taken int…
New Measurement Procedure for Load Flow Evaluation in Medium Voltage Smart Grids
2013
The aim of this paper is to present a new approach for the medium voltage (MV) distribution network load flow analysis, mainly based on power measurement at the low voltage (LV) level of MV/LV distribution substations. This allows to use measurement instruments, usually already installed in the secondary substations, thus achieving an equally reliable measurement system with a lower cost compared to measurements at the MV side. The new approach can be applied using a proper communication system to collect the nodal measurements and an iterative algorithm based on ladder iterative technique (LIT) to compute the load flow. The validity of this method is presented and discussed on the basis of…