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Decarbonization of Summer Cooling Energy Demands of Buildings Employing Absorption Systems in the Framework of Climate Change in Italy
Get PDFTemperatures in the Mediterranean area have gradually risen in the last decades due to climate change, especially in the Italian Peninsula. This phenomenon has increased the cooling needs to ensure thermal comfort in buildings and, consequently, the use of refrigeration machines. Summer air conditioning is carried out mainly using compression machines powered by electricity supplied by the national network. All this contributes to the emission of climate-changing gases. To avoid this disadvantageous chain, compression machines could be replaced by absorption cooling systems powered by solar energy. The energy needs of the buildings in a time are directly proportional to the sum of positive differences between the outdoor air temperature and the indoor set point of the systems (equal to 26°C). The annual sum of hourly temperature differences defined above can be computed for each grid cell thanks to a numerical weather prediction model, namely the Weather Research and Forecasting model, that simulates the hourly temperatures on high-resolution computation grids and over fairly large extents. Maps of cooling consumption for buildings are thus produced. Choosing absorption solar energy-powered systems instead of vapor compression refrigeration systems leads to a drop in electrical energy consumption and therefore in emissions of greenhouse gases. In this work, different hypothetical scenarios of penetration of this technology have been considered. And the subsequent consumption of electricity withdrawn from the national grid has been estimated together with the reduction of greenhouse gas emissions
Numerical Model of Eddy Current Inspection with DC Magnetic Field Associated
Get PDFMost non-destructive techniques can be well represented in a virtual environment, in particular, eddy current testing (ECT) simulation is a useful and well-established tool to predict and represent real inspection situations permitting testing customization in a fast, cheap and efficient way. Conventional ECT generally works with low-intensity magnetic fields, however, for advanced variations of the technique, where external DC magnetic fields can be applied to locally decrease the magnetic permeability, there is no Finite Element Method (FEM) packages available to deal with such nonstandard model. Many authors [1] and [2] have presented this ECT solution for different industrial applications using external DC magnetization to carry nonlinear ferromagnetic materials to the saturation level of the magnetization curve to increase the ECT depth penetration. In general, ECT modelling calculation is benefited by properties of steady-state regime where all magnetic fields are oscillating at the same frequency not permitting through multi-frequency calculation. The present work proposes a simulation solution for such a case where DC magnetic field is associated with ECT. A theoretical model is presented together with experimental results validation
The Effect of Heat Shocks and Freezing–Thawing Cycles on the Mechanical Properties of Natural Building Stones
Get PDFThe damage to rock masses due to the action of freezing is one of the most important factors in the development of landscapes, the performance of civil structures, and the efficiency of mining operations. In this research paper, the effect has been studied on the physical and mechanical performance of seven different natural building rock samples. The testing program included an experimental study on both dry and saturated intact rock samples and therefore, the effect of saturation on the extent of damage on the tested samples has been discussed as well. Based on the obtained results, freezing–thawing cycles increase the porosity of rock samples and decrease the values of P-wave velocity, uniaxial compressive strength, elastic modulus, and Brazilian tensile strength. Moreover, the behavior of different rock types differs to some extent when exposed to weathering cycles under dry and saturated conditions. A multivariate linear regression analysis was used to predict the changes in the physical and mechanical properties of different rock types. It was been shown that with some cautions, the obtained correlations can be generalized for practical cases and can be used to predict the change of rock physical and mechanical properties during the lifetime of rock engineering projects. Such predictions have a high potential of applicability in quite different types of natural stone applications in cold climates. From the stability of structures created in rock materials to the durability of structures created by different natural stones
Corrected Mathematical Models for Motions of the Gyroscope with one Side Free Support
Get PDFAbstract: The recent publications about gyroscope effects explained their physics and described them by mathematical models based on the action of forces and inertial torques of classical mechanics. This new analytical approach finally solved the old problem of the dynamic of rotating objects and showed their kinetic energy is the base of gyroscopic effects. Gyroscopic effects result from the action of the two sets of interrelated inertial torques acting about two axes. Each set contains torques generated by the centrifugal, Coriolis forces, and the change in the angular momentum. Detailed study of the inertial torque of the centrifugal force showed its expression derived with an error of mathematical processing. This error gives a less value for the angular velocity of the slow rotation of the gyroscope about one axis that cannot be measured. The angular velocity of the fast rotation of the gyroscope about the other axis is measured but remains of the same value that gives the expression of the torque with error. This manuscript presents the corrected mathematical model for the motion of the gyroscope suspended from the flexible cord
Our Experience of the First 70 Cases in General Surgery with the New daVinciXi Surgical System
Get PDFWe report our preliminary experience with the new daVinciXi system in general surgery. Since September 2014 to December 2015 we performed 70 operations in general abdominal surgery, mainly in colorectal, using the new daVinciXi. The new system has been thought to overcome the critical issues of multi -quadrant robotic surgery, as the intraoperative collision of the arms. This is allowed by the working set up with parallel arms movements, differently than the daVinciSi system. Here we describe our experience and propose our new trocars layout according to the new working disposal of the Xi system
Daily Task-Oriented Performance Evaluation for Commercially Available Assistive Robotic Manipulators
Get PDFThis preliminary study investigates the performance and cognitive loading of the two commercial wheelchair-mounted assistive robotic manipulators (ARMs) with their original user interfaces (UIs). This study of 20 able-bodied individuals evaluated the performance of two user interfaces, keypad and joystick, using six tasks on an activities of daily living (ADL) task board with environment-independent measures, self-reported cognitive loading and questionnaires. Participants performed tasks with two commercial arms with their original UIs in a randomized order of arm and the six tasks on the adl task board. Performance was evaluated using completion time, throughput, and trajectory parameters. Self-reported measures of workload and questionnaires were also administered. Statistical performance differences were found in the translational tasks (
Enhancing Mechanical Properties of a Lightweight TiAlCrNbVZr Medium-Entropy Alloy: Fine-Tuning Alloy Composition and Thermomechanical Treatment
Get PDFAbstract: The quest to reduce fuel consumption and environmental pollution in the transportation sector has heightened the demand for developing lightweight alloys with enhanced mechanical properties. Accordingly, this study focused on optimizing the mechanical properties of a lightweight Ti65(AlCrNbV)28Zr7 medium entropy alloy (MEA) by strategically adjusting its Al, Cr, Nb, and V elemental contents. Hardness testing indicated a strengthening ability hierarchy of Cr > Al > V > Nb. Furthermore, tensile tests revealed that although a high Cr content significantly enhances strength, it also reduces the ductility of an MEA. Drawing on mechanical insights gained from a previously studied Ti60Al10Cr10Nb10V10 MEA and the present findings, a novel Ti60Al10Cr4Nb10V9Zr7 (Ti60Zr7) MEA was developed. This new alloy retains a single body-centered cubic structure and demonstrated exceptional mechanical performance in tensile testing, with a yield strength of 1066 MPa and 22% ductility. The Ti60Zr7 MEA underwent a series of thermomechanical treatments, including 50% hot rolling, 80% cold rolling, and rapid annealing up to 800 °C at a rate of 25 °C/s. After thermal processing, the Ti60Zr7 MEA not only preserved its single body-centered cubic structure but also achieved a remarkable combination of yield strength (>1200 MPa) and ductility (measured as >15% elongation). These advancements underscore the alloy’s considerable potential for application in sports equipment and transportation vehicles
Optimal Power Flow Scheduling Strategy for Multi-Microgrids with Multi-Time Scale Method
Get PDFAbstract: The energy management of a multi-microgrid (MG) system is essential for its stable and economic operation. This study proposes an optimal power flow scheduling strategy for the energy management of multi-MG systems. At the multi-MG level, the global central controller (GCC) is responsible for managing the MGs. The GCC calculates the amount of power exchanged within the MGs by using a novel optimal energy allocation policy. Based on the energy supply and demand mismatch, MGs are classified as providers and consumers. The GCC collects information, then distributes energy among the consumers and divides benefits to the providers. Each consumer determines the price of the purchased energy from other microgrids based on a priority parameter, in which the local load demand and renewable energy penetration rate are considered as important factors. At the MG level, with the goal of minimising the operating cost of the MG, the energy is controlled from two time scales, namely day-ahead and intraday, to optimise the output power of generators and energy storage devices. Finally, a simulation of a multi-MG system with three MGs demonstrate the effectiveness of the proposed optimal method
Smart Grid Functioning of Solar Electric System Network Based on Complex Accumulation Control
Get PDFAbstract: Voltage maintenance in the distribution system takes place with the use of additional devices. The purpose of the work is to develop a Smart Grid functioning of the solar electric system network based on integrated storage control. Accumulator battery and thermoelectric accumulator as part of the solar electric system network acquire the additional status of voltage regulators in the distribution system. A comprehensive integrated system has been developed for supporting the functioning of the solar electric system network based on a prediction of changes in the battery capacity and power factor. Advanced decisions on change the capacity of the thermoelectric accumulator in redistributes the accumulated electrical energy. Changing the level of transmission of electric energy to the network make it possible to maintain voltage in the distribution system through maintaining the power factor of the network solar electric system. Continuous measurement of the voltage at the input to the hybrid inverter, the voltage at the output from the frequency converter and in the distribution system takes place. The change in the ratio of voltage at the output of the frequency converter and in the distribution system is evaluated. The peak load of the energy system is prevented, reducing the consumption of energy from the network to 14%
Development of a Low-Cost Ball-on-Flat Linear Reciprocating Apparatus: Test Validation Using Ti-6Al-4V and Ti-6Al-4V/Nb2O5 Coatings
Get PDFAbstract: This work aims to propose the development of a low-cost ball-on-flat linear reciprocating apparatus that can have the same attributes of extremely expensive equipment available on the market. For this purpose, the device was constructed following the recommendations of the ASTM G133 standard. The device’s validation was performed trough a comparative study between the ASTM G133 standard and 3D profilometry technique by using Ti-6Al-4V and Ti-6Al-4V/Nb2O5 specimens. The results obtained in the present work were very motivating by showing it was possible to obtain the wear properties with reproducibility through the equipment constructed. The wear tests showed that the functionalization of the Ti-6Al-4V alloy with Nb2O5 coatings increased the wear resistance of the biomaterial, reducing the wear volume about 80.1 % when compared to the base material. Finally, this work demonstrated (i) the effectiveness and reproducibility of the device built to carry out microwear tests, (ii) the increase in resistance to the mechanical wear process conferred by the Nb2O5 film on the Ti-6Al-4V alloy and (iii) the powerful impact of the 3D profilometry technique when compared to the ASTM G133 standard for wear volume determination