scholarly journals Comparative assessment of the inline and branching design strategies based on the compound technique

2020 ◽  
Author(s):  
Ali Triki
Keyword(s):  
Pressure Wave ◽  
Control Strategies ◽  
Steel Pipe ◽  
Hydraulic Systems ◽  
Design Strategies ◽  
Trade Off ◽  
Dead End ◽  
Significant Attenuation ◽  
Pressure Magnitude ◽  
Short Section

Abstract The inline or branching water hammer control strategies, which are based on the insertion of compound plastic short-penstock or inline section at the transient-induced region of main pipes, illustrated a promising ability to upgrade steel pipe-based hydraulic systems concerning the extension of admissible pressure level. In this respect, prior results suggested that the specific layout utilizing an (HDPE–LDPE) compound short-penstock (where the (HDPE) sub-short-penstock is attached to the main steel pipe and the (LDPE) sub-short-penstock corresponds to the short-penstock dead-end side) provided significant attenuation of pressure magnitude. Concurrently, recent studies concluded that the (HDPE–LDPE) compound short-section-based inline strategy provided substantial attenuation of pressure magnitude. However, these strategies illustrated a drawback relying on the expansion of the period of pressure wave oscillations. Accordingly, this study assessed and compared the capacities of the compound technique concerning the trade-off between the magnitude-attenuation and the period-expansion of pressure wave oscillations. The findings of these analyses showed that the (HDPE–LDPE) compound short-penstock particular setup of the branching strategy allowed the best trade-off between the attenuation of magnitude and the period expansion of pressure wave oscillations. Furthermore, results showed the competitiveness of the latter upgrading strategy as compared to the (HDPE) or (LDPE) main pipe-based renewed hydraulic systems.

Benchmarking the Dual and Compound Techniques-Based Branching Design Strategy Used for Upgrading of Pressurized Hydraulic Systems

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
Waêl Ben Amira ◽  
Ali Triki
Keyword(s):  
Pressure Wave ◽  
Plastic Material ◽  
Conventional Technique ◽  
Steel Pipe ◽  
Low Density Polyethylene ◽  
Piping System ◽  
Low Density ◽  
Hydraulic Systems ◽  
Transient Pressure ◽  
Pipe Flow Model

Abstract Prior research has recognized that the compound- and dual-technique-based branching redesign measures, used as alternatives to the conventional technique-based one, were effective in upgrading steel pipe-based pressurized hydraulic systems. Principally, the compound technique used two different plastic material types for the short-penstock instead of the single material type utilized in the conventional technique. However, the dual technique is based on splitting the single penstock installed in the conventional technique into a set of dual subpenstocks placed at each connection of the main-piping system to hydraulic parts. This handling aimed at improving the conventional technique efficiency with regard to the tradeoff between the magnitude attenuation and period expansion effects of the transient pressure-wave signal. Accordingly, this study proposed a comprehensive comparison between the compound- and dual-technique-based branching strategy with particular focus on the tradeoff between the two last parameters. The plastic material types demonstrated in this study included the high- or low-density polyethylene. The application addressed a waterhammer maneuver initiated into a reservoir-steel-pipe-valve system. Numerical computations used the method of characteristics for the discretization of the 1D extended pressurized-pipe flow model, embedding the Kelvin–Voigt and Vitkovsky formulations. The finding of this study suggested that the high- or low-density polyethylene (HDPE–LDPE) setup of the compound technique is the most prominent protected system setup, providing an acceptable tradeoff between the attenuation of magnitude and the expansion of the period of pressure-wave oscillation.

scholarly journals The costs of keeping schools open during the COVID-19 pandemic

2021 ◽  
Author(s):  
David Haw ◽  
Giovanni Forchini ◽  
Paula Christen ◽  
Sumali Bajaj ◽  
Alexandra Hogan ◽  
...  
Keyword(s):  
Economic Model ◽  
Control Strategies ◽  
Retail Trade ◽  
Economic Gain ◽  
Economic Sectors ◽  
Trade Off ◽  
Hospital Capacity ◽  
The United Kingdom ◽  
Economic Production ◽  
Personal Services

Abstract There is a trade-off between restrictions on the education sector and other economic sectors in the control of SARS-CoV-2 transmission. Here we integrate a dynamic model of SARS-CoV-2 transmission with a 63-sector economic model reflecting sectoral heterogeneity in transmission and economic interdependence between sectors. We identify control strategies which optimize economic production while keeping schools and universities operational, and constraining infections such that emergency hospital capacity is not exceeded. We estimate an economic gain of between £163bn (24%) and £205bn (31%) for the United Kingdom compared to a blanket lockdown of non-essential activities over six months, depending on hospital capacity. Sectors identified as priorities for closures are contact-intensive, produce few crucial inputs for other sectors and/or are less economically productive. Partial closures over some months are required for retail trade, hospitality, accommodation, creative activities, arts, entertainment, and personal services including hairdressing and beauty treatments under most scenarios.

scholarly journals Simulation of a Hydraulic Load Sensing Proportional Valve

2018 ◽  
Author(s):  
Sanjar Mirzaliev ◽  
Kungratbai Sharipov
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Control Strategies ◽  
Level Of Detail ◽  
Department Of Energy ◽  
Fluid Power ◽  
Hydraulic Systems ◽  
Proportional Valve ◽  
Load Sensing ◽  
The U.S

Nowadays energy saving is a topical issue due to increasing fuel costs and this aspect is amplified by more stringent emissions regulations that impact on vehicle development. A recent study conducted by the U.S. Department of Energy shows that about five percent of the U.S. energy consumption is transmitted by fluid power equipment. Nevertheless, this study also shows that the efficiency of fluid power averages 21 percent. This offers a huge opportunity to improve the current state-of-the-art of fluid power machines, in particular to improve the energy consumption of current applications. These facts dictate a continuous strive toward improvements and more efficient solutions: to accomplish this objective a strong reduction of hydraulic losses and better control strategies of the hydraulic systems are needed. In fluid power, there exist many techniques to reduce/recover energy losses of the conventional layouts, e.g. load sensing, electrohydraulic flow matching, independent metering, etc. One of the most efficient ways to analyze these different layouts and identify the best hydraulic solution is done through virtual simulations instead of prototyping, since the latter involves higher investment costs to deliver the product into the market. However, to build a fluid power machine virtual model, some problems arise relative to different aspects, for instance: loads on actuators (both linear and rotational) are not constant and pumps are driven by a real engine whose speed depends on required torque. Furthermore, it is important to achieve higher level of detail to simulate each component in the circuit: the greater detail, the better the machine behavior is portrayed, but it obviously entails heavy impact on simulation time and computational resources. Therefore, there is a need to create mathematical model of components and systems with sufficient level of detail to easily acquire all those phenomena necessary to correctly evaluate machine performance and make modifications to the fluid power component design. In this context, a hydraulic proportional valve PVG 32 by Danfoss is taken as an object of study, its performance is analyzed with suitable mathematical model and simulation is done to observe closeness of a model to the laboratory experiment.

scholarly journals Circulating Brucella species in wild animals of the Serengeti ecosystem, Tanzania

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
R. M. Sambu ◽  
C. Mathew ◽  
H. E. Nonga ◽  
A. S. Lukambagire ◽  
R. B. Yapi ◽  
...  
Keyword(s):  
Control Strategies ◽  
Domestic Animals ◽  
Wild Animal ◽  
Contact Network ◽  
Human Brucellosis ◽  
Wild Animals ◽  
Cross Sectional ◽  
Serengeti Ecosystem ◽  
Dead End ◽  
Surveillance Programs

Abstract Background Brucellosis is a bacterial zoonosis of public health and economic importance worldwide. It affects a number of domestic animals, wild animals and humans. Human brucellosis originates from either livestock or wildlife. The species of Brucella circulating in wild animals in Tanzania is largely unknown due to insufficient surveillance. This study was carried out to identify Brucella species found in selected wildlife hosts in the Serengeti ecosystem. Methodology The study used a total of 189 archived samples that were obtained from cross-sectional studies previously conducted between 2000 and 2017 in the Serengeti ecosystem in Tanzania. Whole blood, serum and amniotic fluid collected from buffalos, lions, wildebeest, impala, zebra and hyena were available for DNA extraction. Multiplex polymerase chain reaction for B. abortus, B. melitensis, B. ovis and B. suis (AMOS PCR) and quantitative real-time PCR (qPCR) targeting the bcsp31 and IS711 genes for Brucella genus detection and the IS711 targets alkB for B. abortus and BMEI1162 for B. melitensis were used to detect Brucella strains. Results Out of the 189 samples tested, 12 (6.35 %) and 22 (11.6 %) were positive to AMOS-PCR and qPCR, respectively. Most of the positive samples were from lions (52.6 %) and buffaloes (19.6 %). Other animals that were positive included: wildebeest (13.6 %), impala (13.6 %), zebra (4.5 %) and hyena (4.5 %). Out of 22 positive samples, 16 (66.7 %) were identified as B. abortus and the other six samples did not amplify for neither B. abortus nor B. melitensis. Conclusions The detection of Brucella DNA in archived wild animal samples shows testing potential of samples collected from this population. The zoonotic species B. abortus and B. melitensis detected in wild animals have previously been reported in livestock and humans in the region. The findings suggest that, due to the contact network, some of the identified wild animal hosts in this study could be reservoirs for infections in domestic animals and humans within the Serengeti ecosystem while others are likely dead-end hosts. One Health control strategies and continuous surveillance programs in other wildlife reserved areas should be implemented to help predicting transmission in livestock and humans in the region.

Exploring the performances of the dual technique-based water hammer redesign strategy in water supply systems

2019 ◽  
Vol 69 (1) ◽  
pp. 6-17 ◽  
Author(s):  
Mounir Trabelsi ◽  
Ali Triki
Keyword(s):  
Pressure Wave ◽  
Oscillation Period ◽  
Conventional Technique ◽  
Water Hammer ◽  
Water Supply Systems ◽  
Piping System ◽  
Wave Oscillation ◽  
Pressure Surge ◽  
Short Section ◽  
Steel Piping

Abstract This paper explored and compared the effectiveness of the inline and branching redesign strategies-based dual technique, implemented to enhance the conventional technique skills in terms of attenuation of positive and negative pressure surge magnitudes and limitation of the spreading of pressure wave oscillation period. Basically, this technique is based on splitting the single inline or branched plastic short-section, used in the conventional technique, into a couple of two sub-short-sections made of two distinct plastic material types. Investigations addressed positive and negative surge initiated water hammer events. Additionally, high and low density polyethylene materials were utilized for sub-short-section material. Results illustrated the reliability of the dual technique in protecting hydraulic systems from excessive pressure rise and drop, and evidenced that the (HDPE/LDPE) sub-short-sections' combination (where the former sub-short-section is attached to the sensitive region of the steel piping system parts, while the latter is attached to the second extremity of the steel piping system) is the most prominent configuration providing the best trade-off between pressure surge attenuation, and pressure wave oscillation period spreading. Lastly, it was found that the pressure head peak (or crest) and the pressure wave oscillation period values were markedly sensitive to the (HDPE) sub-short-section length and diameter.

Position control and performance analysis of hydraulic system using two pump-controlling strategies

2018 ◽  
Vol 233 (9) ◽  
pp. 1093-1105 ◽  
Author(s):  
Gyan Wrat ◽  
Prabhat Ranjan ◽  
Mohit Bhola ◽  
Santosh Kumar Mishra ◽  
J Das
Keyword(s):  
Control Strategy ◽  
Position Control ◽  
Control Strategies ◽  
Speed Control ◽  
Hydraulic Systems ◽  
Proportional Integral Derivative ◽  
Proportional Integral Derivative Controller ◽  
Proportional Integral ◽  
Actuation System ◽  
Swash Plate

The role of hydraulic systems is quite evident especially in the case of heavy machineries employed in industries, where the utilisation of high forces amid large stiffness is the prerequisite. Nevertheless, there has been substantial effort put forward in the development of advanced control strategies which finally addressed the issue of the position control. Proportional–integral–derivative control strategy happens to be one among them, which is a versatile and widely renowned approach involved in the position control in this study. Although, it is quite frequently observed that the hydraulic actuation system possesses strong nonlinearities. In this article, two different actuator position control strategies, that is, swash plate control of main pump and speed control strategy of prime mover are compared. In swash plate control strategy, the proportional–integral–derivative controller adjusts the swash plate of main pump through servo mechanism, whereas in the speed control strategy, the proportional–integral–derivative controller adjusts the speed of the electric motor through variable-frequency drive. For this purpose, two MATLAB-Simulink models are developed and validated experimentally. It is found that swash plate control strategy has better dynamic and control performance than the speed control strategy catering same position demand of the linear actuator.

scholarly journals Mathematical modeling of the Mojave Solar Plants

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4197 ◽  
Author(s):  
Antonio J. Gallego ◽  
Manuel Macías ◽  
Fernando de de Castilla ◽  
Eduardo F. Camacho
Keyword(s):  
Mathematical Modeling ◽  
Large Scale ◽  
Control Strategies ◽  
Research Topics ◽  
Trade Off ◽  
Computational Burden ◽  
Main Research ◽  
Advanced Control ◽  
Overall Efficiency ◽  
Tuning Process

Competitiveness of solar energy is one of current main research topics. Overall efficiency of solar plants can be improved by using advanced control strategies. To design and tuning properly advanced control strategies, a mathematical model of the plant is needed. The model has to fulfill two important points: (1) It has to reproduce accurately the dynamics of the real system; and (2) since the model is used to test advanced control strategies, its computational burden has to be as low as possible. This trade-off is essential to optimize the tuning process of the controller and minimize the commissioning time. In this paper, the modeling of the large-scale commercial solar trough plants Mojave Beta and Mojave Alpha is presented. These two models were used to test advanced control strategies to operate the plants.

scholarly journals Assessment of inline technique-based water hammer control strategy in water supply systems

2019 ◽  
Vol 68 (7) ◽  
pp. 562-572 ◽  
Author(s):  
Ridha Ben Iffa ◽  
Ali Triki
Keyword(s):  
Water Supply ◽  
Plastic Material ◽  
Pressure Head ◽  
Oscillation Period ◽  
Water Hammer ◽  
Steel Pipe ◽  
Water Supply Systems ◽  
Wave Oscillation ◽  
Supply Systems ◽  
Short Section

Abstract This article discusses and compares the effectiveness of the compound and dual technique-based inline strategy used to upgrade existing steel pipe-based water supply systems. Basically, these techniques are based on splitting the single inline short section, used in the conventional technique, into a couple of two sub-short sections made of two distinct plastic material types: high- and low-density polyethylene (HDPE) and (LDPE). The 1D unconventional water hammer solver based on the method of characteristics was used for numerical computations. Results evidenced that the specific setup of the compound technique based on (HDPE-LDPE) sub-short sections (where the former sub-short section is attached to the hydraulic parts, while the latter is attached to the main steel pipe) is the most prominent configuration providing an acceptable trade-off between attenuation of pressure head surge, and limitation of excessive wave oscillation period spreading. Furthermore, this compound technique setup allowed more important pressure head peak (or crest) attenuation as compared with the dual technique based on (LDPE-LDPE) sub-short sections; while inducing about similar values of wave oscillation period spreading.

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