Insulation Arrangement Research Articles

EXPERIMENTAL STUDY ON THE FACTORS AFFECTING THE INSULATION PERFORMANCE OF FLAME-RETARDANT MULTILAYER INSULATION MATERIALS

Flame-retardant multilayer insulation materials act as effective thermal insulation blankets of cryogenic containers that store flammable and explosive cryogenic liquids. This study used standard static liquid nitrogen boil-off calorimetry to test the insulation performance of eight groups of flame-retardant multilayer insulation materials with different wrapping parameters. The effects of four factors, namely the layer density, seaming process, number of reflector layer, and variable-density multilayer insulation arrangement, on the insulation performance were analysed. Three layer densities were considered: 4.47, 3.08, and 2.50 layers/mm. Two types of seaming processes were discussed: the overlapped and fold-over seaming processes. Three numbers of reflector layers were considered: 60, 70, and 80. Two variable-density multilayer insulation arrangements with similar thicknesses were discussed: 10-10-40 and 20-20-20 layers of reflectors allocated for low-, medium- and high-density segments. The conclusions are as follows: Decreasing the layer density enhances the performance of multilayer insulation; Using the fold-over seaming process results in less heat flux and lower apparent thermal conductivity; An increase in the number of reflector layers weakens radiative heat transfer, resulting in better thermal insulation; Furthermore, for a given wrapping thickness, reducing the number of reflectors appropriately in low- and medium-density segments improves the insulation performance; Optimizing and controlling the layer density of each density segment are also essential for variable-density multilayer insulation effects. This study provides supporting theories and reference data for practical engineering applications.

Seismic behavior of AAC infill walls insulated with cementitious lightweight panels in reinforced concrete frames

Autoclaved aerated concrete (AAC) walls are commonly used as infill walls in reinforced concrete frames. Thermal properties of infill walls in cold regions can be improved by bonding additional insulation panels. In this study, eight half-scale, one-bay, one-story reinforced concrete frames with insulated AAC infill walls were tested under cyclic increasing in-plane (IP) displacement excursions to simulate earthquake demands. Two different methods of insulation arrangements were studied by using mineral-based cementitious materials. In addition to in-plane loading, out-of-plane (OOP) and combined in-plane and out-of-plane (IP + OOP) tests were conducted under constant axial load and increasing cyclic displacement excursions. It was observed that insulated AAC infill walls had limited deformation capacity with premature failure of the insulation plates. The observed damage limits of the insulated AAC infills were compared with the codes' drift ratio limits. It was concluded that such walls should be classified as fragile components with limited drift capacity.

Failure Diagnosis and Root-Cause Analysis of In-Service and Defective Distribution Transformers

Diagnostic data of transformers are essential in determining their integrity and to estimate their reliability. Such diagnostic data is not available for distribution transformers as only meagre attempts are made to accumulate this information. The reason for lack of such attention is attributed to the compromise made to meet financial constraints and cost-cutting measures. It is needless to emphasize the significance of these diagnostic data in evading premature failures and enhancing the accuracy of the maintenance program. Overall, the concepts of diagnostic methods are well defined regarding power transformers, but cannot be extended to distribution transformers. This paper attempts to fill this gap by measuring the diagnostic data from in-service and defective distribution transformers. For this purpose, eight transformers (six in-service, two defective) showing deviations in their diagnostic status were selected from a group. As per their kVA rating and operating status, the chosen transformers were categorized into three sets and their integrity of insulation and winding-core arrangement were analyzed. Later, the root-cause analysis was performed on defective transformers to understand their failure reasons and possibilities to evade them. The pertinent data obtained are quite valuable for making decisions regarding reliability-oriented maintenance and for extending its potential in the distributed generation.

Ex Situ Conservation of Large and Small Plant Populations Illustrates Limitations of Common Conservation Metrics

Premise of research. Ex situ plant conservation can be improved through genetic analysis. One area of interest is the relative value of conserving smaller or larger populations and how sampling strategies for these might differ. Current practice emphasizes collecting large sample sizes from some populations and limiting sampling from others and aims for the capture of allele diversity exceeding predetermined thresholds at the species level. Evaluating how well botanic garden collections can capture the genetic diversity of populations of different sizes can help refine guidance on conservation efforts. Methodology. A model species, Pseudophoenix sargentii (Arecaceae), was chosen for its disjunct and insular range, variation in population size, and presence in collections. We compared 123 in situ plants from three discrete island populations with 94 ex situ conservation specimens via 10 microsatellite markers. Comparison of allelic diversity among the wild populations and collections allowed for the evaluation of genetic capture. Pivotal results. Genetic distance analysis, fixation indexes, and Bayesian clustering analysis show discrete in situ geographic structure and close affinity between ex situ collections and in situ source populations. Yet collections from just the largest population met the Global Strategy for Plant Conservation Target 9 threshold for conservation success for that source population, for other smaller populations, and for all populations together. Conclusions. Percent of genetic capture thresholds may need revision, as such thresholds overlook important diversity. Efficient genetic capture is maximized by emphasizing unique maternal lineages and limiting half-siblings in a collection, but this selectivity must be balanced against the need for redundancy in living collections. Large and small populations each contribute to meeting genetic diversity goals. We recommend that botanic gardens and their networks develop conservation priorities based on genetic diversity and resources, carefully consider existing thresholds for conservation success, define metrics for ex situ conservation goals, and integrate analysis into ex situ conservation efforts.

Sound signal of the Himalayan marmot in its insular range

The range of Himalayan marmot (Marmota himalayana Hodgson, 1841) has an insular character, as it is limited by ecological and geographical barriers: in the north, northeast and east, these are deserts and the Loess Plateau, in the west - mountain peaks covered with glaciers and rivers, in the south - forests of the southern macro slope of the Himalayas. Only in the northwest of the range there is an ecological corridor. The geographical isolation of populations of marmots provokes the divergence of alarm call, which is one of the obvious genetically determined features. The results of cluster analysis based on a complex of features of the sound signal coincide with the results of analysis using nuclear and mitochondrial DNA. The projection of variability on the structure and history of the landscape contributes to understand the ecological and geographical factors of divergence as the basis for the process of speciation.

INFLUENCE OF DENSITY AND THICKNESS ON POLYSTYRENE INSULATED CONCRETE BLOCK WALLS

Expanded polystyrene is known of its useful thermal properties and is widely used as an insulation material. Optimum performance depends on the design and selection of a product. Density and thickness of polystyrene boards were investigated using two chambers built of concrete blocks. The chambers were in the form of four block walls 20 cm in thickness, 1m by 1m size and 1m in height. Wood boards were used in roofs. The two chambers were identical except for insulation arrangements of the blocks. One chamber was built using bricks without insulation while the other chamber involved polystyrene insulated block walls. .In order to assess the influence of density; two types of materials were considered; Wall-mate polystyrene of an average density 26 to 28 Kg/m3 and Roof-mate polystyrene of an average density of 32 to 35 Kg/m3. Boxes of 60 cm x 60 cm x 60 cm made of polystyrene sheets were fabricated with thicknesses of 4, 5, 8 and 10 cm. Ambient temperature and temperature inside each chamber or polystyrene box were recorded using 5TE sensors and a data logger. Hourly records through specified periods of time were logged for the insulation systems used. Temperature changes within the chambers were studied and the influence of the board thickness and material density were reported. It was found that low-density polystyrene provides better insulation. Improvement due to a thickness of polystyrene boards was noted. The results provide a helpful guide for the specification and design works using polystyrene material.

Numerical study of insulation structure characteristics and arrangement effects on cell trapping using alternative current insulating based dielectrophoresis

Insulator-based dielectrophoresis is a recently developed technique in which insulating posts are used to produce non-uniformity in the electric field in a microchannel. This study presents the effects of insulating posts geometry and arrangement on the trapping efficiency of red blood cells in an alternating current- Insulator-based dielectrophoresis system. Microchannels containing square, circular and diamond-shaped posts with particles under the influence of positive dielectrophoresis force and fluid flow were considered. Finite element method was used to compute the velocity of the flow and electric field. The numerical method was verified by comparing the numerical results with experimental data. Two distinct criteria for examining particle trapping for distinct shapes and arrangements of insulating posts were introduced. Particle tracing simulation was implemented to observe particle trapping and compare the trapping performance of systems with distinct posts. As shown in the results for the system with circular and square posts, insulators should be narrowed to improve particle trapping, while diamond post should be widened to increase the trapping efficiency. In addition, the particle tracing results showed that microchannel with square posts is more efficient in particle trapping.

Sound proofing and thermal properties of an innovative viscoelastic treatment for the turboprop aircraft fuselage

Low-resilience polyurethane foams including several additive constituents were synthesized to improve their vibro-acoustic performances, as well as the thermal insulation. viscoelastic polymer additive can attenuate vibrations and absorb sound energy. the vibro-acoustic properties of two innovative viscoelastic treatments fabricated with polyurethane foams are discussed in this paper using a typical aeronautical panel test setup. Since an aircraft insulation arrangement must provide both noise and thermal insulation for the specified operating conditions and expected thermal comfort of passengers, the thermal conductivity of the samples has been examined assuming a testing range between 20 °C (room temperature) and − 40 °C (cruise altitude). the results highlighted an optimal behavior of the novel viscoelastic foams in terms of both acoustic and thermal performance, offering a very interesting self-embedded solution with a good weight to performance ratio, compared to standard blanket composed by extra viscoelastic treatments.

Thermal analysis of in-situ microwave casting for efficient processing

In the present work, in-situ microwave casting was analyzed for higher efficiency while aluminum casting at 2.45 GHz and 1400 W. Models of setup with different insulation arrangements were generated using a software tool. Simulation was carried out to find the optimum casting conditions. Results revealed that complete insulation of mold assembly enhances energy saving and reduces melting time; however, higher mold preheating results in longer solidification time and coarse grains in the cast. Mold assembly without insulation showed poor efficiency. Optimum results were obtained in a mold assembly consisting insulated pouring basin and charge with bare mold and sprue.

Cameraria ohridella: The first record in Central Asia

Data on the formation of the invasive range of Cameraria ohridella in Russia and data on the first record of this invasive phytophage of the horse chestnut in Kazakhstan are given. For the first time, this pest was found in the horse chestnut landscaping planting in Almaty in 2014. It is supposed that, in Central Asia, Cameraria ohridella forms an insular range, which is isolated from its European range by the areas of Siberia and Western and Northern Kazakhstan where the horse chestnut does not grow.

Condition monitoring of high voltage transformers using Fiber Bragg Grating Sensor

High voltage (HV) power apparatus determines the stability of any electrical power system. Failure of such apparatus is mainly due to damage of insulation normally caused by the Partial Discharge (PD). Therefore PD measurements are globally considered as most essential and favored testing procedure for most of the HV power apparatus. Online condition monitoring may help to take proper corrective action at proper time, which reduces unscheduled downtime and can save money for electrical supply utilities.HV power transformers are being considered as heart of any electrical system and they have received much attention in recent years. In HV transformers, PD is one of the main reasons for degradation of insulation quality. Therefore its detection can provide early indication of the insulation failures of transformers. PD can be traced through direct measurement of current, electromagnetic radiation, chemical changes or acoustic emission. Electrical, acoustic, chemical and optical methods of PD measurement are the popularly accepted methods of PD detection in the high voltage (HV) power transformers. Over the past decades various PD sensors have been developed, most of these require electrical connections closed to measurement site and electrical wirings and amplifiers for transmission of measured signals. Placing electrical components and wirings closer to HV terminals is difficult for installation of such sensors; moreover, due to proximity of HV terminals these sensors suffer from electromagnetic interference (EMI).In this context, development of optical fiber based PD sensor can be promising as the optical fibers are made of dielectric material so can be easily placed inside the equipment without any additional insulation arrangements. On the other hand, it has very low transmission loss; therefore, the measured signal can be transmitted to the sub-station control room without use of any electrical amplification system and it is free from EMI. In this work, a Fiber Bragg Grating (FBG) based optical PD sensor has been developed for online detection of PD within HV power transformer. The shift in wavelength of FBG due to impulsive acoustic pressure generated during PD event has been used for the detection. The performance of the developed FBG based sensor has been validated experimentally with standard electrical (IEC60270) PD measurement system. Experimental results show that the developed sensor is a suitable substitute for conventional PD measuring system and it can be placed inside the apparatus.

SU-E-T-410: Fringe Stability and Phase Shift Measurements in a Michelson Interferometer for Optical Calorimetry

Purpose: To identify the variables limiting the resolution of a Michelson interferometer used to measure phase shifts (PS) in water as part of a radiometric calorimeter. Methods: We investigated the output stability of a He-Ne laser and a laser diode. The short and long term stability of the fringe pattern in a Michelson interferometer was tested with different types of lasers, thermal insulation arrangements, damping systems and optical mounts to optimize system performance. PS were induced by electrically heating water in a 1 cm quartz cuvette located in one of the interferometer arms. The PS was calculated from fringe intensity changes and compared to a calculated PS using thermocouple-measured temperature changes in the water. Results: The intensity of the laser diode is more stable, but the gas laser’s profile is more suitable for fringe analysis and has better temporal coherence. The laser requires a warm-up time of 4 hours before its output is stabilized (SNR>95). The fringe’s stability strongly depends on the thermal insulation. When the interferometer is exposed to ambient temperature swings of 0.7 K, it is not possible to stabilize the fringe pattern. Enclosing the system in a 2.5 cm-thick Styrofoam box improves the SNR, but further insulationmore » will be needed to increase the SNR above 50. High frequency noise is significantly reduced by damping the system.Inducing a temperature rise in water, starting at 299 K, the average temperature increase for a 2π PS is 0.29 ± 0.02 K and the proportionality constant is -21.1 ± 0.8 radians/K. This is 5.8% lower than the calculated value using the thermocouple. Conclusion: Interferometric PS measurements of temperature may provide an alternative to thermistors for water calorimetry. The resolution of the current prototype is limited by ambient temperature stability. Calculated and measured thermally-induced PS in water agreed to within 5.8%.« less

A statistical study on the combined effects of wall thermal mass and thermal resistance on internal air temperatures

Statistical analyses are important for real-world validation of theoretical model predictions. In this article, a statistical analysis of real data shows empirically how thermal resistance, thermal mass, building design, season and external air temperature collectively affect indoor air temperature. A simple, four-point, diurnal, temperature-by-time profile is used to summarise daily thermal performance and is used as the response variable for the analysis of performance. The findings from the statistical analysis imply that, at least for moderate climates, the best performing construction/design will be one in which insulation and thermal mass arrangements can be dynamically altered to suit weather and season.

Temperature profile optimization for microwave sintering of bulk Ni–Al2O3 functionally graded materials

Bulk multilayer graded Ni–Al2O3 samples have been sintered under heating by millimeter-wave radiation using a gyrotron system for high-temperature materials processing. By using a purposely designed thermal insulation arrangement, the temperature profile has been adjusted along the concentration gradient to accommodate for different sintering temperatures of the components. The sintered samples have flat boundaries between layers, and their microstructure is free from cracks and delamination. In addition to metal-ceramic graded transitions, metal-ceramic-metal graded insulator structures have also been fabricated.

Efficacy of Three Vaccines in Protecting Western Scrub-Jays (Aphelocoma californica) from Experimental Infection with West Nile Virus: Implications for Vaccination of Island Scrub-Jays (Aphelocoma insularis)

The devastating effect of West Nile virus (WNV) on the avifauna of North America has led zoo managers and conservationists to attempt to protect vulnerable species through vaccination. The Island Scrub-Jay (Aphelocoma insularis) is one such species, being a corvid with a highly restricted insular range. Herein, we used congeneric Western Scrub-Jays (Aphelocoma californica) to test the efficacy of three WNV vaccines in protecting jays from an experimental challenge with WNV: (1) the Fort Dodge West Nile-Innovator(®) DNA equine vaccine, (2) an experimental DNA plasmid vaccine, pCBWN, and (3) the Merial Recombitek(®) equine vaccine. Vaccine efficacy after challenge was compared with naïve and nonvaccinated positive controls and a group of naturally immune jays. Overall, vaccination lowered peak viremia compared with nonvaccinated positive controls, but some WNV-related pathology persisted and the viremia was sufficient to possibly infect susceptible vector mosquitoes. The Fort Dodge West Nile-Innovator DNA equine vaccine and the pCBWN vaccine provided humoral immune priming and limited side effects. Five of the six birds vaccinated with the Merial Recombitek vaccine, including a vaccinated, non-WNV challenged control, developed extensive necrotic lesions in the pectoral muscle at the vaccine inoculation sites, which were attributed to the Merial vaccine. In light of the well-documented devastating effects of high morbidity and mortality associated with WNV infection in corvids, vaccination of Island Scrub-Jays with either the Fort Dodge West Nile-Innovator DNA vaccine or the pCBWN vaccine may increase the numbers of birds that would survive an epizootic should WNV become established on Santa Cruz Island.

Experimental study on premixed CH 4/air mixture combustion in micro Swiss-roll combustors

Excess enthalpy combustion is a promising approach to stabilize flame in micro-combustors. Using a Swiss-roll combustor configuration, excess enthalpy combustion can be conveniently achieved. In this work, three types of Swiss-roll combustors with double spiral-shaped channels were designed and fabricated. The combustors were tested using methane/air mixtures of various equivalence ratios. Both temperature distributions and extinction limits were determined for each combustor configuration at different methane mass flow rates. Results indicate that the Swiss-roll combustors developed in the current study greatly enhance combustion stability in center regions of the combustors. At the same time, excess enthalpy combustors of the Swiss-roll configuration significantly extend the extinction limits of methane/air mixtures. In addition, the effects of combustor configurations and thermal insulation arrangements on temperature distributions and extinction limits were evaluated. With heat losses to the environment being significant, the use of thermal insulations further enhances the flame stability in center regions of the Swiss-roll combustors and extends flammable ranges.

Genetic diversity and phylogenetic relationships of Mabuya spp. (Squamata: Scincidae) from western Indian Ocean islands

AbstractWestern Indian Ocean islands (excluding Madagascar) are inhabited by at least five species of the lizard genus Mabuya, for which diversity and inter-island phylogenetic relationships are still unclear, particularly concerning island populations of M. maculilabris, M. comorensis and M. striata. With a comprehensive sampling across the Comoros archipelago and the islands of Zanzibar and Pemba (Tanzania) we use molecular data and previously published sequences of these species to describe genetic variation across their insular range and explore the possible distinction of insular populations of the different species, contributing to the clarification of their status and knowledge of their colonization patterns. We describe patterns of cryptic diversity within M. comorensis, revealing a West to East colonization of the Comoros archipelago and clarify the status of Malagasy populations of this species. Cryptic variation is also observed within M. maculilabris and M. striata, and the status of several continental and island populations discussed. M. sechellensis is shown to be paraphyletic relative to M. wrightii. Available data for all Afro-Malagasy Mabuya reveals additional possible instances of paraphyly within some species but does not allow for further resolution of basal relationships within this group, pointing to rapid and simultaneous divergences within this group and the need for multiple independent markers to recover the history of this group.

A Repetitive High Voltage Pulse Adder Based on Solid State Switches

A repetitive high voltage pulse adder based on solid state switches with isolated recharge is described. All capacitors in the modulator are recharged separately through a corresponding magnetic core transformer by a common high frequency power supply. This circuit configuration simplifies the insulation design and arrangement. This scheme is suitable for high frequency pulse discharge due to its high charge efficiency. At the same time it retains the inherent switch protection capability similar to a solid-state Marx modulator. In our present work, a 22-stage test modulator has been built and successfully operated at output voltage of 20 kV with repetitive rate of 20 kHz, rise time of 150 ns and pulse width of 3 μs. The primary experiments verified the system feasibility.

Impact of air intrusion on the wind uplift performance of fully bonded roofing assemblies

Wind performance investigation is critical in the design of durable roofing assemblies. In North America, mainly two types of low slope roofs, conventional and inverted, are in practice depending on the placement of the membrane in the assembly. As part of the conventional low-sloped roofs, in a fully bonded assembly (FBA) the insulation is mechanically attached and waterproof membrane is bonded to the insulation using adhesives. Recent field investigations of roof failures after major hurricanes indicated that FBA are susceptible to high wind events. To understand the response of the FBA under dynamic environment, an extensive experimental study has been carried out by the SIGDERS – Special Interest Group for Dynamic Evaluation of Roofing Systems, at the National Research Council. The present study focuses on the impact of air intrusion on wind uplift performance of these assemblies. Airflow control is usually achieved by including a barrier/retarder in the roofing assembly. Assembly with barrier improved the wind uplift rating by two fold when compared to an assembly without barrier. Use of staggered insulation arrangement can provide similar air retarding effect as a barrier and can therefore sustain similar wind uplift pressures compared to an assembly with barrier.

Molecular phylogeny and historical biogeography of the land snail genus Solatopupa (Pulmonata) in the peri-Tyrrhenian area

The land snail genus Solatopupa consists of six species and has a peri-Tyrrhenian distribution; most of the species have a very narrow range and all of them except one ( Solatopupa cianensis, which inhabits porphyritic rocks) are strictly bound to calcareous substrates. One species ( Solatopupa guidoni) is limited to Sardinia, Corsica, and Elba Island. Because the potential for dispersal of these snails is low, the insular range of this species has been traditionally related to the Oligocenic detachment of the Sardinia–Corsica microplate from the Iberian plate and its subsequent rotation towards the Italian peninsula. In this study, we used sequences of three mitochondrial and one nuclear gene to reconstruct the evolutionary history of the genus. Our phylogenetic results are consistent with the genetic relationships found using allozymes, but contrast with the phylogenetic hypotheses based on karyology and morphology. Molecular clock estimates indicate that the main cladogenetic events in the genus occurred between the middle Miocene and the middle-late Pliocene. Patterns of phylogenetic relationships and geological considerations suggest that the cladogenesis of the genus can be explained by vicariant (tectonic) processes. Our datings do not support a causal relation between the split of S. guidoni from its continental sister taxon and the initial phases of the detachment of the Corsica–Sardinia microplate from the mainland. On the contrary, time estimates coincide with the very last phase of detachment of the microplate (from 5 to 3 Myrs ago). Overall, our molecular clock estimates are in good agreement with the latest geological views on the tectonic evolution of the peri-Tyrrhenian area.