Field Performance Study Research Articles

The comparative field performance study of heat pipe evacuated tube collectors with standard design manifold header and parallel flow manifold header based on the metal foam structural element

The paper deals with an experimental thermal performance comparison of standard design heat pipe evacuated tube collector and collector with parallel flow manifold header with metal foam structural element which was developed by authors in their previous work. The used data were obtained during experimental simultaneous operation of two interconnected solar systems at the Centre of Renewable Energy Sources, Kosice, Slovakia during the months of April and May in various weather and climatic conditions. Manifold header with metal foam structural element partially eliminates deficiencies of standard design manifold headers by changing of heat transfer medium stream conducting to each condenser, reducing the internal fluid volume and introducing of new structural element to manifold header design – heat exchange chamber made of metal foam which increases the heat exchange surface of condenser. Presented data consist of a selection from all measurements taken during experimental operation, when solar collector with manifold header based on metal foam showed a performance increase around 25%, and reduced thermal inertia of the solar collector at operation with changing intensity of solar insolation, which leads to an overall improvement in function of the solar system.

Flow Field Numerical Simulation and Performance Study of Two-Stage Superheated Electrical Steam Trap

In order to promote the localization of critical valve in ultra-supercritical thermal power generating unit, a two-stage superheated electrical steam trap was designed and developed. Its structure and operation principle was introduced. Three-dimensional numerical simulation of the internal turbulent fluid field was performed by using Fluent of computational fluid dynamics software. The results show that the superposed design of associated reaction with multiaperture equalizer and guide sleeve was adopted in the two-stage superheated steam trap. The internal flow field become more uniform, local maximum velocity reached 37.2m/s. The brush erosion of valve seat is reduced and the service life is increased. Success rate of the first sample's trial-manufacture is greatly improved by using CFD simulation experiment in the process of design. Development cycle is shortened and the cost is reduced, which can provide a reference for two-stage superheated steam trap design.

Field Evaluation of 12 Soil Moisture Sensors on a Sandy Loam Soil in Lu’an, Subtropical Monsoon Climate Region, China

An in situ field test with three indices of stability, sensitivity and accuracy on 12 soil moisture sensors was carried out in a sandy loam soil located in Lu’an at the subtropical monsoon climate region (China). The results showed that the majority of sensors were above 0.98 with a higher stability degree except for HT-DR-601(0.348) and DZN3 (0.661). Almost all sensors had a sensitive response to a certain amount of precipitation but Hydra Probe II was an exception. Trime-pico, SM300, ML2X, SWR6 and DH-FDR had a higher accuracy than 0.785, while DZN3 and HT-DR-601 were very lower. The mean differences of SM300, Trime-pico and Uni_SM were between -1% and 0, while HTSMS-02, DH-FDR, SWR6, ML2X, MP-4C and MP-323 were between -5% and -1%. DZN3 had the largest values of -17.8%. Finally, SM300, Trime-pico, ML2X, SWR6 and DH-FDR were got scores above 9 points while MP-323 and Uni_SM were above 8.4, showing an outstanding performance. The field performance study could provide some choices for the large-scale filed applications and the drought monitoring system.

Comparative field performance study of concentrator augmented array with two system configurations

The paper describes the system and experimental evaluation of an evacuated tube heat pipe collector array augmented with a novel design internal concentrator having a direct flow absorber and tested in the north–south and east–west align configurations under real outdoor conditions. External and internal concentrators have the potential to supply higher generator inlet temperatures needed for solar driven cooling systems. However, internal concentrator augmented solar collectors can further reduce heat losses and increase output temperatures. It is shown that collector outlet temperatures of 110 °C or more is possible and can be efficiently used to drive solar cooling systems with higher coefficient of performance (COP). The evacuated tube collector array augmented with a novely designed internal concentrator having a direct flow absorber in the north–south alignment was found to be more energy efficient with larger temperature lift and outlet and inlet temperature differential and substantial improvement in thermal performance compared to its east–west align configuration due to shorter connection piping connecting the internal concentrator augmented CPC to the evacuated tube heat pipe collector array.

Comparative field performance study of flat plate and heat pipe evacuated tube collectors (ETCs) for domestic water heating systems in a temperate climate

This paper presents a year round energy performance monitoring results of two solar water heaters with 4 m 2 flat plate and 3 m 2 heat pipe evacuated tube collectors (ETCs)operating under the same weather conditions in Dublin, Ireland. The energy performance of the two systems was compared on daily, monthly and yearly basis. Results obtained showed that for an annual total in-plane solar insolation of 1087 kWh m −2, a total of 1984 kWh and 2056 kWh of heat energy were collected by the 4 m 2 FPC and 3 m 2 ETC systems respectively. Over the year, a unit area of the FPC and ETC each generated 496 kWh m −2 and 681 kWh m −2 of heat respectively. For 3149.7 kWh and 3053.6 kWh of auxiliary energy supplied to the FPC and ETC systems their annual solar fractions (SFs) were 38.6% and 40.2% respectively. The annual average collector efficiencies were 46.1% and 60.7% while the system efficiencies were 37.9% and 50.3% respectively for the FPC and ETC respectively. Economic analysis showed that both solar water heating (SWH) systems are not economically viable with NPVs ranging between −€4,264 and −€652 while simple payback periods (SPPs) varied between 13 years and 48.5 years.

Gauge, Cutting Structure, Torque Control Components—What Really Counts for Optimal Tool Face Control With FC Drill Bits?

Summary Tool-face control is widely regarded as one of the greatest challenges when drilling directionally with an FC (fixed cutter) drill bit on a positive displacement motor (PDM). Tool-face offset is proportional to the torque generated by the bit. FC bits, by nature, generate high levels of torque. If an external force acting on the bit causes an FC bit to over-engage, a large change in downhole torque is typically produced, which causes rotation of the drillstring and loss of tool-face orientation. It is therefore desirable for an FC bit to produce a torque response that does not vary greatly with changes in the external forces applied. This paper examines the effect of varied components of an FC drill bit to determine the key design requirements to deliver a smooth torque response and improved directional performance. This includes evaluation of the results from a comprehensive series of laboratory tests to determine the effectiveness of a number of varied, removable torque controlling components (TCC). The goal was to establish a configuration that would provide predictable torque response to applied weight on bit (WOB), allowing cutting structures to be independently optimized for overall higher penetration rates. A novel gauge geometry was engineered to reduce drag and deliver a smoother borehole. This would provide less torque when sliding and beneficial gauge pad interaction with the borehole when in rotating mode. Field performance studies clearly demonstrate that matching TCC, an optimized cutting structure, and gauge geometry to a steerable assembly delivers smooth torque response and improved directional control. Benefits within rotary vertical applications are also demonstrated. Successful application has resulted in significant time and cost savings.

Construction of an Embankment with a Fly and Bottom Ash Mixture: Field Performance Study

Fly ash and bottom ash are coal combustion by-products (CCBPs) that are generated in large quantities throughout the world. It is often economical to dispose ash as mixtures rather than separately; that notwithstanding, only a few studies have been performed to investigate the behavior of fly and bottom ash mixtures, particularly those with high contents of fly ash. Also, there is very limited data available in the literature on the field performance of structures constructed using ash mixtures. This paper describes the construction and the instrumentation of a demonstration embankment built with an ash mixture (60:40 by weight of fly ash:bottom ash) on State Road 641, Terre Haute, Ind. Monitoring of the demonstration embankment was conducted for a period of 1year from the start of construction of the embankment. The settlement of the embankment stabilized approximately 5months after the end of its construction. According to horizontal inclinometer readings, the differential settlement at the top of the embankment is about 5mm. Results from field quality control tests performed during construction of the demonstration embankment and monitoring data from vertical and horizontal inclinometers and settlement plates indicate that the ash mixture investigated can be considered an acceptable embankment construction material.

Field Performance Study of a Regional WiMAX Network for Intelligent Transportation System Applications

Of the various advanced wireless communication technologies used for intelligent transportation systems (ITS), WiMAX has recently received much attention because of its potential to provide broadband network connectivity, large coverage areas, quality assurance, and mobile access. However, few studies have focused on the deployment, operational, and performance issues of using WiMAX networks for ITS applications in a real roadway environment. This study performed a field performance evaluation of a regional WiMAX network in West Virginia by using important network metrics, including uplink and downlink throughput, signal strength, and connectivity level. On the basis of performance analysis, this paper discusses the feasibility and suitability of a regional WiMAX network deployment for a wireless sensor-based traffic surveillance system in terms of frequency, power, and client side radio requirements. This study provides an insight into the feasibility of using WiMAX to address ITS applications. It will benefit transportation agencies and other stakeholders to support decision making in the deployment and operation of a WiMAX-based ITS network in the future.

A case study of long-term field performance of check-dams in mitigation of soil erosion in Jiangjia stream, China

This paper examines the long-term field performance of the check-dams in mitigation of soil erosion in the Duozhao catchment of Jiangjia stream, southwest China. Since their construction between 1979 and 1982, the check-dams have been functioning effectively. The examination is made via comparisons between the environmental conditions of the Duozhao catchment with its adjacent Menqian catchment in the stream, because no check dams were constructed in the Menqian catchment. The examination is based on recent field investigations and aerial photograph analyses, and covers four aspects: (a) bed gradients of catchment channels; (b) stability of bank slopes; (c) rates of land erosion; and (d) vegetations on bank slopes. The field data demonstrate that the check-dams have had the following good functions for mitigation of soil erosion: (1) restricting the channel depth and lateral erosions, (2) protecting the channel erosion base, (3) reducing the bed gradients of debris-flow channels, (4) fixing the channel bed, (5) stabilizing the bank slopes, as well as (6) facilitating the growth of vegetations.

Influence of capacitive effects on the dynamic of a CNTFET by Monte Carlo method

We present a study of carbon nanotube field effect transistors (CNTFET) operation and performance using Monte Carlo simulation including phonon scattering. In CNTFETs, operating in the quantum capacitance regime, the low driving electric field in the channel yields a high fraction of ballistic transport. In terms of ballisticity, I ON/ I OFF ratio and intrinsic delay, the performance of 100 nm-long CNTFET is shown to be as high as that of much smaller Si transistors.

Comparative Study of Seed Vigor and Field Performance in Niger (<i>Guizotia abyssinica</i> Cass.) Collected from Three Districts of Nepal

Comparative study of seed vigor, viability tests and field performance of niger (Guizotia abyssinica Cass.) seeds collected from three different places of Nepal were carried out. Although the seeds showed 95.7-98.0% germination in laboratory conditions and nearly the same level of viability in triphenyl tetrazolium chloride (TTC) test, field emergence was only 77.5% and 78.2% for the seeds of Jhapa and Sunsari, respectively, and 68.0% for the seeds of Bhojpur. Only about 75% of the emerged seedlings survived in the field. Seedling survival counted as the percentage of total seeds sown was about 68.1% and 69.0% for the seeds of Jhapa and Sunsari and only 53.1% for the seeds collected from Bhojpur. J. Inst. Agric. Anim. Sci. 2003 24:37-41

Assembly and performance of hybrid-VRLA cells and batteries

Several commercial-grade hybrid-VRLA and AGM-VRLA cells and batteries have been assembled and tested under varying charge–discharge rates in a temperature range between 50 and −40 °C. Impedance studies on hybrid-VRLA and AGM-VRLA cells have been conducted to reflect on their resistive and capacitive values. A linear relationship is found to exist between logarithmic state-of-charge values and ohmic impedance of batteries. In general, hybrid-VRLA cells and batteries perform better than their AGM-VRLA counterpart. A field-performance study conducted on AGM-VRLA and hybrid-VRLA batteries for solar-lighting application also suggests the latter to be superior.

Comparison of seed-derived with micropropagated male-sterile plants of Tagetes erecta L. for F1 hybrid seed production

SummaryTo multiply large number of male-sterile marigold plants for F1 hybrid seed production, an efficient protocol for in vitro cloning of field-grown differentiated male sterile plants has been developed. A comparative field performance study of tissue culture and seed-derived male sterile plants of two marigold genotypes was undertaken to test the possibility of using micropropagated plants in hybrid seed production. Tissue culture raised plants of both genotypes had superior field performance to the seed-derived counterparts. These plants were more vigorous in growth, i.e. in terms of plant height, number of secondary branches and number of leaves and plant spread, while the leaf chlorophyll contents were equal to that of seedling plants. Flowering was earlier by 2-3 weeks and the number of flowers per plant was also higher in such plants. Repeated hand pollination of sterile flowers with bagged flowers of cv. Pusa Narangi Gainda showed that seed set and bold seed yield were higher or almost comparable with the seed-derived plants. The results clearly indicate that the tissue culture can be adopted for the successful cloning of male-sterile plants, which could then be utilized for producing F1 seeds with higher quantities of bold seeds with better storability.

Louisiana Experience with Crumb Rubber-Modified Hot-Mix Asphalt Pavement

A comparative study of laboratory and field performance of several applications of crumb rubber-modified (CRM) hot-mix asphalt in Louisiana is presented. Eight CRM asphalt pavement sections were constructed by eight different CRM processes or applications. These eight CRM sections were built at five state highway projects. A control section with conventional asphalt mixture was constructed at each project to compare with the performance of pavement sections built with CRM asphalt mixtures. To evaluate the mixture characteristics of the CRM and conventional mixes, laboratory tests of Marshall stability and flow, indirect tensile strength and strain, and indirect tensile resilient modulus were conducted on field compacted Marshall specimens. Comparisons of the field performances of the pavements were achieved through roadway core air void analysis, rut-depth measurement, international roughness index, pavement structure numbers measured through the Dynaflect (dynamic deflection determination) system, and visual inspections of cracks. The results indicated that the conventional mixtures exhibited higher laboratory strength characteristics than the CRM mixtures. The pavement sections constructed with CRM asphalt mixtures showed overall better performance indices (rut depth, fatigue cracks, and international roughness index numbers) than the corresponding control sections after 5 to 7 years of traffic.

Performance of Louisiana’s Chip Seal and Microsurfacing Program, 2002

A 5-year field performance study was conducted of the 1995–1996 Chip Seal and Microsurfacing projects with a summary of data generated by the Louisiana Department of Transportation and Development’s pavement management group. The pavement management data set includes performance indicators such as the international roughness index, crack analysis, rut depth, and ground-penetrating radar thickness. A subjective survey designed for maintenance surfacing was developed and used on this same set of projects. The pavement condition rating was examined from the point of pretreatment and annually until spring of 2001. The survey suggests that treatments will improve a pavement’s initial condition, but no conclusion can be drawn on the effect on pavement condition index (PCI) over time compared with untreated pavements, as all pavements’ PCI curves are similar and are independent of PCI before treatment. General observations for chip seal projects are as follows: the median PCI was 75 after 52 months with a significant reduction in cracking; 20% of the projects showed moderate to heavy bleeding; rutting was not evident; and measurement for skid resistance was very good. For a life expectancy of 5 years, the equivalent annual cost (EAC) of a chip seal is approximately 27 cents a year. For micro-surfacing projects, the median PCI of microsurface sections is approximately 85 after 60 months of service with significantly fewer cracks detected after treatment. Projects with 0.5-in. initial rut showed substantial reduction after treatment. The friction numbers (FN) for smooth tire are in the low teens to low thirties on 50% of the projects. The lower numbers are attributed to a combination of the use of limestone and high asphalt content. Sandstone sections exhibited FNs in the 50s. For a life expectancy of 6 years, the EAC is about 49 cents a year.

Effectiveness of Portland Cement and Lime in Stabilizing Clay Soils

Pavement subgrades constructed with clay soils can cause significant pavement distress because of moisture-induced volume changes and low subgrade support values. Lime is well known for its ability to stabilize plastic clays; however, portland cement also provides highly effective clay stabilization, usually with the added benefit of higher strength gain. Stabilizing clays with cement or lime can improve subgrade properties at a lower cost than either removing and replacing material or increasing the base thickness to reduce subgrade stress. The clay soil stabilization mechanism for the calcium-based stabilizers portland cement and lime is reviewed. These materials modify soil properties through cation exchange, flocculation and agglomeration, and pozzolanic reaction. Additionally, cement provides hydration products, which increase the strength and support values of the subgrade materials as well as enhance the permanence of the treatment. Comparative laboratory and field performance studies by others, focusing on stabilization of clay soils with portland cement or lime, are critically reviewed. Several factors affecting stabilization are discussed, including stabilizer test procedures, dosage effects to soil properties, mixing, compaction, and gradation and pulverization. Additionally, durability of cement and lime as stabilizers is reviewed, including wetting and drying, freezing and thawing, leaching, and long-term field performance. The research reviewed indicates that, if proportioned and applied properly, both cement and lime can effectively improve the engineering properties of clay soils over the life of a pavement. The results presented provide a guide to the engineer about the property changes to expect when using portland cement and lime with regard to volume stability, strength, and durability.

Preliminary results of composite liner field performance study

This paper presents preliminary results of a study of the field performance of composite liners. The purpose of the study is to evaluate the ability of composite liners to contain municipal solid waste (MSW) leachate. The paper presents data for double-lined MSW landfills having composite top liners consisting of a geomembrane (GMB) upper component and a compacted clay liner (CCL) lower component. Data on flow volumes and flow constituents for the leachate collection and removal system (LCRS) and the leakage detection system (LDS) components of the double liner system are analyzed to assess whether leakage has occurred through the composite top liner. Data for nine MSW landfill cells with monitoring periods of up to eight years are presented. Preliminary results indicate that the nine composite liners are performing well and are effective in containing MSW leachate.

Fiber-reinforced cement composites

Historical developments mechanics of fibers basic concepts of mechanical properties - tension, bending constitutive materials mixture proportions - mixing and casting procedures properties of freshly mixed FRC properties of hardened FRC compression, tension and flexure FRC under impact and fatigue loading creep, shrinkage and long-term performance of FRC plastic drying shrinkage fiber-reinforced shotcrete glass fiber reinforced cement (GFRF) thin sheet products slurry infiltrated fiber concrete (SIFCON) use of FRC in structural components field performance and case studies.

Estimation of Reliability in Field-Performance Studies]: Discussion

Estimation of Reliability in Field-Performance Studies]: Discussion

Estimation of Reliability in Field-Performance Studies]: Discussion

Estimation of Reliability in Field-Performance Studies]: Discussion