Heterogeneous Arrival and Departure M/M/1 Queue with Vacation and Service Breakdown

This paper deals with the study of M/M/1 queue with heterogeneous arrival and departure with the provision of server vacations and breakdowns. Customer arrive service facilities with poison process and exponential service time distribution. In this paper we find the mean queue length, mean waiting time in queue and system, average number of customers in the system. The generating function method is used to find these measures of performance. The numerical results are obtained to cite the applicability of model in the real life situations. Key words: Heterogeneous; Generating function; Vacation; Breakdown; Repai

Fluxon Dynamics of a Long Josephson Junction with Two-gap Superconductors

We investigate the phase dynamics of a long Josephson junction (LJJ) with two-gap superconductors. In this junction, two channels for tunneling between the adjacent superconductor (S) layers as well as one interband channel within each S layer are available for a Cooper pair. Due to the interplay between the conventional and interband Josephson effects, the LJJ can exhibit unusual phase dynamics. Accounting for excitation of a stable 2$\pi$-phase texture arising from the interband Josephson effect, we find that the critical current between the S layers may become both spatially and temporally modulated. The spatial critical current modulation behaves as either a potential well or barrier, depending on the symmetry of superconducting order parameter, and modifies the Josephson vortex trajectories. We find that these changes in phase dynamics result in emission of electromagnetic waves as the Josephson vortex passes through the region of the 2$\pi$-phase texture. We discuss the effects of this radiation emission on the current-voltage characteristics of the junction.Comment: 14 pages, 6 figure

Comparison of different cereal grains for hydroponic fodder production in locally constructed polyhouse at Khumaltar, Lalitpur, Nepal

Hydroponic fodder production technology involves an intensive method of quality fodder production in less space and in a shorter duration. An experiment was conducted to compare the different cereal grains under hydroponic fodder production for the fodder yield, fodder quality, and per unit production cost in a locally constructed polyhouse. Maize (Zea mays L.), oat (Avena sativa L.) and wheat (Triticum aestivum L.) were evaluated as the treatments. The experiment was carried out in Completely Randomized Design (CRD) with 12 replications at National Pasture and Fodder Research Program in July 2017 and July 2018. The observations were taken on plant morphological characters, fodder yield (including root mat), fodder nutrient composition and expenses in variable costs. The results of the study showed that the fodder yield varied significantly (P<0.05) for different cereal grains. The hydroponic fodder yields from each kg grain were recorded higher in fodder oat (7.96 kg) compared to wheat (6.76 kg) and maize (5.32 kg). Similarly, the crude protein (CP) content of the fodder was higher in wheat (16.16%) compared to oat (13.96%) and maize (12.51%). The cost of hydroponic maize, oat and wheat fodder production were obtained as recorded NPR 20.64, 24.67 and 18.76 per kg, respectively

Anchorage of Headed Reinforcing Bars in Concrete

Headed reinforcing bars serve as a viable alternative to hooked bars for anchorage in concrete because they provide a more efficient anchorage mechanism and limit congestion of the reinforcement. This study is part of a comprehensive study of the anchorage behavior of the headed bars. The work described in this report includes tests of 32 No. 8 headed bars anchored in simulated column-foundation joints represented by bars anchored in slabs, all but two with reinforcement in the plane of the slab, and six lapped-slplice specimens without confining reinforcement containing No. 6 headed bars and an analysis of these tests along with test results from 23 studies by other researchers of 84 exterior, seven roof-level interior, and seven knee beam-column joints subjected to reversed cyclic loading. The headed bars in the column-foundation joint specimens had net bearing areas ranging from 4 to 15 times the area of the bar Ab; some of the headed bars contained large obstructions adjacent to the bearing face of the head that exceeded the dimensional limits for HA heads in ASTM A970-16; embedment lengths ranged from 6 to 8.5 in.; reinforcement in a plane perpendicular to the headed bars included combinations of bars placed symmetrically about the headed bar, parallel and close to the long edges of the specimen, bars placed symmetrically about and close to the headed bar in the short direction of the specimen, and bars oriented in both the long and short directions of the specimen; concrete compressive strengths ranged from 4,200 to 8,620 psi; and stresses in the bars at failure ranged from 49,500 to 117,000 psi. The No. 6 headed bars had a net bearing area of 4Ab and a lap length of 12 in. The center-to-center spacing between the spliced bars was 1.67, 2.33, or 3.53 bar diameters db; clear concrete cover to the bars was 2 in.; concrete compressive strengths averaged 6,360 and 10,950 psi; and stresses in the bars at failure ranged from 75,010 to 83,560 psi. For the beam-column joints subjected to reversed cyclic loading, headed bar sizes ranged between D12 (No. 4) and D36 (No. 11), net bearing areas ranged from 1.7 to 11.4Ab, and embedment lengths ranged from 8 to 22.6db; concrete compressive strengths ranged from 3,480 to 21,520 psi and steel yield strengths ranged from 53,650 to 149,930 psi; all but four specimens contained hoops, spaced at 2.2 to 6.8db (1.8 to 5.9 in.), as confining reinforcement parallel to the headed bar within the joint region; clear cover and minimum center-to-center spacing between the bars ranged from 1.4 to 9.9db and from 2 to 11.2db, respectively. Experimental anchorage strengths are compared with values based on descriptive equations for anchorage strength and design provisions for development length of headed bars for members with concrete compressive strengths up to 16,000 psi and steel yield strengths up to 120,000 psi that recognize the contribution of confining reinforcement without specifying minimum limits on bar spacing or clear cover. The descriptive equations and design provisions were developed based on tests of simulated beam-column joints under monotonic loading as part of the comprehensive study. The comparisons are used to expand the applicability of the descriptive equations to members subjected to reversed cyclic loading and develop simplified design guidelines allowing for the use of headed reinforcing bars in wide range of reinforced concrete members. Changes in the provisions of ACI 318-14 for the development length of headed bars and in ASTM A970 for head dimension requirements are also proposed. The results of this study show that reinforcement perpendicular to headed bars in columnfoundation joints does not improve the anchorage strength. Headed bars with obstructions exceeding the dimensional limits for HA heads in ASTM A970-16 provide adequate anchorage strength. Headed bars did not provide sufficient anchorage in knee beam-column joints subjected to reversed cyclic loading. The descriptive equations and proposed design provisions developed based headed bars in beam-column joint specimens tested under monotonic loading, in which the anchorage strength of the headed bar is a function of embedment length, concrete compressive strength, bar spacing, bar diameter, and confining reinforcement within the joint region, are applicable to a wide range of reinforced concrete members, including beam-column joints subjected reversed cyclic loading, lap splices, and column-foundation joints, and allow the minimum clear spacing of 3db between headed bars permitted in joints in special moment frames in accordance with Section 18.8.5.2 of ACI 318-14 to be reduced to 1db, allowing for the use of more closely spaced headed bars. The anchorage strength of the headed bars calculated using anchorage provisions of Chapter 17 of ACI 318-14 with a strength reduction factor of 1.0 provides a very conservative and highly variable estimate of anchorage strength for headed bars compared to the proposed design provisions

Headed Bars in Beam-Column Joints Subjected to Reversed Cyclic Loading

Descriptive equations developed for the anchorage strength of headed bars in beam-column joints under monotonic load are evaluated for beam-column joints subjected to reversed cyclic loading. Test results from 23 studies that include 84 exterior and seven roof-level interior beam-column joints are used in the evaluation. Concrete compressive strengths and reinforcement yield strengths ranged from 3480 to 21,500 psi (24 to 148 MPa) and 53,700 to 150,000 psi (370 to 1030 MPa), respectively. Headed bar sizes ranged from slightly smaller than a No. 4 (No. 13) to No. 11 (No. 36) with net-bearing areas ranging from 1.7 to 8.6 times the bar area. The embedment lengths and center-to-center spacing between the headed bars ranged from eight to 18 bar diameters and from two to eight bar diameters, respectively. Analysis of the test data shows that descriptive equations based on headed bars under monotonic loading are also applicable to headed bars in beam-column joints subjected to reversed cyclic loading. These comparisons were used to justify the single approach used within the ACI Building Code for calculating the development length of headed bars

Soil Physico-Bio-Chemical Properties Under Poplar + Indian Mustard Inter Cropping System

A field experiment was conducted during the winter seasons of 2008-10 at Agroforestry Research Centre, Pantnagar, India with aim to examine the effect of different levels of recommended Nitrogen (N): Phosphorus (P): Potassium (K) (NPK) on soil physico-bio-chemical properties under varying poplar tree densities with mustard introcropping. Lower soil bulk density was recorded under 1000 trees/ha density compared to sole crop in both the year. Soil bulk density (BD) decreased underneath trees. However, soil pH, available N and K were not influenced by tree density in both the years. Electrical conductivity (EC) and soil organic carbon (SOC) increased underneath trees of either tree density compared to sole crop in both the years. Significantly (P<0.05) higher available P was recorded under 1000 trees/ha density compared to 250 and 500 trees/ha densities including sole crop in 2008-09. Similarly, soil microbial biomass carbon (SMBC) increased with increasing the tree density and significantly (P<0.01) higher value was recorded under 1000 trees/ha density compared to sole crop and sparse density both the years except 2009-10, where 500 and 1000 trees/ha densities remain statistically at par. On the other hand, dehydrogenase activity (DA) was maximum under 500 trees/ha density compared to sole crop and 1000 trees/ha density in both the years. Among the fertility levels, the maximum SOC and available N were recorded with 75% compared to 50, 100 and 125% of recommended NPK in 2008-09, except available N with 100% of recommended NPK. But, available P was more with 100% of recommended NPK in 2008-09. Similarly, maximum SMBC were recorded with 75 % compared to higher doses of recommended NPK in both the years. Similarly, BD, EC, SOC, available N, P and K were recorded maximum and soil pH minimum in 0-15 cm soil layers compared deeper layers.Journal of Nepal Agricultural Research Council Vol.1 2015 pp.14-2