The design of low vibration doubly salient motors

Structural Finite Element Analysis is used to investigate potential improvements in the design of low vibration, doubly salient switched reluctance motors (SRMs). The natural modes of vibration of a 4-pole round-stator are examined. The dynamic response of the machine stator when electromagnetic forces are applied at the stator poles is fully examined in this paper. The 4-pole, round-stator SRM is compared with a common square-stator motor as well as a novel square-stator structure, in which the poles are positioned at the square corners. Other machine design cues aimed at reducing vibration, such as the addition of pole fillets and the choice of suitable back iron width, are investigated

Low-loss Polymer Optical Components and Cladding Interferometric Devices Inscribed Using Femtosecond Laser Inscription

We present the development of low-loss polymer optical fiber components and interferometric devices in perfluorinated multimode fibers like CYTOP and silica fibers, respectively. This includes the inscription of usable fiber Bragg gratings, chirped gratings and Fabry-Perot cavities in multimode gradient index fiber using a femtosecond laser inscription. We present the successful demonstration of interferometric devices such as Mach-Zehnder filters and Fabry-Perot cavities inscribed in the cladding of a single mode silica optical fiber. The advantages of these particular progressive sensors are discussed

Retrofit of a church with linear viscous dampers

The church of Agios Ioannis Prodromos in the village of Askas, Cyprus, contains a vast cycle of important and rare Byzantine wall paintings dating from the 15th and 16th centuries. Because of its importance to the cultural heritage of Cyprus, the church has been selected as one of the monuments to be studied in an INCO-MED project for the Conservation of Historical Mediterranean sites by innovative seismic protection techniques (CHIME). The computational model developed for the church is presented, as well as the measurements obtained by hammer-impact excitation. The fine-tuning of the selected computational model to match the dynamic characteristics obtained from the site measurements is also discussed. The model was used to test analytically the cost-effectiveness of damping devices in providing the best earthquake protection to the church without spoiling its monumental value

Health-monitoring and system-identification of an ancient aqueduct

An important historical monument of Cyprus is an aqueduct that was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the case-study monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). Detailed drawings of the aqueduct obtained from the Department of Antiquities of Cyprus have been used for the development of a computational model. The model was fine-tuned through the measurement of the dynamic characteristics of the aqueduct using forced and ambient vibrations. It should be noted that measurement of the dynamic characteristics of the structure were performed twice in a period of three years (June of 2004 and May of 2007). Significant differences were noted and they are attributed to soil structure interaction effects due to seasonal variations of the water-level in a nearby salt-lake. The system identification results for both cases are presented here. This monument was used to test the effectiveness of shape memory alloy (SMA) pre-stressed devices, which were developed during the course of the project, in protecting it without spoiling its monumental value

Application of shape memory alloy prestressing devices on an ancient aqueduct

The results of the application of shape memory alloy (SMA) prestressing devices on an aqueduct are presented in this paper. The aqueduct was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the casestudy monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). The Department of Antiquities of Cyprus, acting in a pioneering way, have given their permission to apply the devices in order to investigate their effectiveness in providing protection to the monument against probable catastrophic effects of earthquake excitation. The dynamic characteristics of the structure were determined in two separate occasions and computational models were developed that matched very closely the dynamic characteristics of the structure. In this paper the experimental setup and the measured changes in the dynamic characteristics of the monument after the application of the SMA devices are described

Seismic protection of an ancient aqueduct using SMA devices

AIP Conference Proceedings Volume 1020, Issue PART 1, 2008, Pages 61-68The effectiveness of the use of Cu-based shape memory alloy (SMA) prestressing devices on an ancient aqueduct is examined in this paper. The dynamic characteristics of the aqueduct were measured within the span of three years and computational models were developed that matched very closely its dynamic behaviour. Using this as a bench mark, SMA prestressing devices were applied on the structure and the effects on its dynamic characteristics were assessed. It was noted that the SMA prestressing devices have a significant effect on the dynamic response of the structure. This is attributed to the stiffening of the structure due to the increase in contact between the masonry units and hence the increase of its stiffness through the increase of the modulus of elasticity of the masonry matrix. It can be concluded that the SMA prestressing devices can provide an inconspicuous means of stiffening masonry structures and increase their resistance to earthquake loads. © 2008 American Institute of Physics

Seismic protection of an aqueduct by innovative techniques

The effectiveness of the use of Cu‐based shape memory alloy (SMA) prestressing devices on an ancient aqueduct is examined in this paper. The dynamic characteristics of the aqueduct were measured within the span of three years and computational models were developed that matched very closely its dynamic behaviour. Using this as a bench mark, SMA prestressing devices were applied on the structure and the effects on its dynamic characteristics were assessed. It was noted that the SMA prestressing devices have a significant effect on the dynamic response of the structure. This is attributed to the stiffening of the structure due to the increase in contact between the masonry units and hence the increase of its stiffness through the increase of the modulus of elasticity of the masonry matrix. It can be concluded that the SMA prestressing devices can provide an inconspicuous means of stiffening masonry structures and increase their resistance to earthquake loads

Economic Evaluation of New-type Energy Geo-structures in Residential Buildings. A Case Study in Moderate Mediterranean Climate

Shallow Geothermal Energy Systems (SGESs) are Renewable Energy Systems (RES), which are applied in the residential sector through the use of Ground Source Heat Pumps (GSHPs). GSHPs are coupled with Ground Heat Exchangers (GHEs), where heat is absorbed or rejected through a network of pipes in the ground. GSHPs have not yet thrived in the RES market because of their high initial costs and long payback periods. Two Energy Geo-Structure (EGS) systems, in specific the foundation (or energy) piles and the foundation bed of a residential building in moderate climate Mediterranean conditions in the island of Cyprus, were computationally modeled by Aresti et al. [1]. A theoretically typical house with nearly Zero Energy Building (nZEB) characteristics was examined, with estimated heating and cooling loads used as inputs to investigate the performance of the EGS-GSHP systems. Both systems were shown to exhibit steady performance and high Coefficient of Performance (COP) values, making them an alternative RES solution for integration in residential building. In this study the above-mentioned systems were evaluated economically by comparison with a conventional high- and low-performance Air Source Heat Pump (ASHP) systems. Although various methods could be used to evaluate the economic benefits of the systems, to simplify the study, only the difference in the cost of the two systems is used here through the Simple Payback Period (SPP) and the Discounted Payback Period (DPP) methods. The monthly loads and average monthly COP values of each system, as well as the lifespan and the cost of the HP replacement were considered. It is noted that the costs related to grout filling and the borehole extraction are not included, as in any case the buildings foundations would be constructed, therefore no cost is added. The cost of the HPs was based on the local market (as of year 2020) at EUR8500 for a high efficiency ASHP, EUR4500 for a low-efficiency ASHP, and at EUR6500 for a GSHP

A cost and environmental impact analysis of Ground Source Heat Pumps in European climates

Ground Source Heat Pumps (GSHPs) are used for space heating and cooling. They form a Renewable Energy System (RES), combined with Ground Heat Exchangers (GHEs) to extract or reject heat from/to the ground. GHEs come in various types such as vertical or horizontal. Compared to conventional Air Source Heat Pumps (ASHPs), GSHPs, although having a higher installation cost, exhibit a higher coefficient of performance (COP). The aim of this paper is to address whether it is economically feasible to install a GSHP as an alternative to an ASHP. In addition, as the environmental impact of a system does not lie in a single aspect, e.g., the cost or COP, it is also useful to identify whether a GSHP system is indeed a sufficiently overall greener solution than an ASHP system. To this end, a case study of a residential building with nearly Zero Energy Building (nZEB) characteristics, for certain heating and cooling loads is considered in Mediterranean, Central and Northern Europe climate conditions. Using GLD software, a GSHP system is studied for a typical vertical U-tube GHE configuration to estimate the length of the boreholes and the COP of the systems. Then, an environmental impact analysis is presented for different GSHP systems in comparison to ASHP systems. The systems undergo a Life Cycle Analysis (LCA), with the annual heating and cooling load as functional unit. The openLCA software is used with the ReCiPe method with a mid-point perspective. The Global Warming Potential impact category is studied. Finally, a cost analysis is presented for the GSHP systems in comparison to ASHP systems and the total energy savings is obtained per case. Hence, the cost breakeven point is estimated per case and is used to assess the viability of each system. It turns out that ASHP systems of specifically designed inverter technology ducted series HP can be highly competitive with GSHP systems

Comparative study of multimode CYTOP graded index and single-mode silica fibre Bragg grating array for the mode shape capturing of a free-free metal beam

The work described in this paper involved two different material fibre Bragg grating (FBG) arrays, investigating their performance as quasi-distributed sensors by capturing the vibrating response of a free-free metal beam close to its resonance frequencies. A six meter length of low-loss, gradient-index, multimode CYTOP fibre and of SMF-28 were used for the inscription of multiple FBG sensors using a femtosecond laser inscription method. The FBG arrays were multiplexed in the wavelength domain using a high-speed commercial demodulator, from which we recovered wavelengthand time-dependent displacement information. We compared the vibration response of the two arrays and using a novel computation algorithm we extract the first mode shape of the free-free metal beam that was exited at its first resonance frequency using a vibrating force.Part of SPIE Proceedings Vol. 988