Dynamic behaviour of curved piles

The paper presents an analytical model and associated computer program which is developed to investigate the dynamic behaviour of curved piles embedded in a homogeneous elastic half-space and subjected to forced harmonic vertical vibration, wherein the movement of piles in the axial and lateral directions are considered. The analysis accounts for a soil-pile interaction in a simplified way and predicts the response of such foundations. Equivalent stiffness and damping parameters of pile in longitudinal and horizontal directions have been studied and typical results have been presented. A parametric study of the dimensionless amplitudes in longitudinal and lateral directions is also presented. The directions are found to depend on the frequency of vibrations, slenderness ratio and curvature of pile. Analytical results are compared with experimental ones.     

面向中小企业的区域性虚拟组织实施策略与方法研究

通过分析区域性中小企业合作的基本组织形式及其特点,以当前中小企业群体中常见的中心卫星结构和企业集群两种典型合作方式及其混合结构为基础,提出建立垂直集成型、水平集成型和混合型虚拟组织的原则和方法,同时讨论了不同类型区域性虚拟组织的适用领域和实施策略。     

Next-generation wearable networks

Increased research in microelectronics, wireless communications, and human-computer interaction, particularly augmented-reality applications, has made a symbiotic system technically feasible. Wearable computing, or wearware, focuses on making this technology useful in everyday life, particularly for integrating contextual data with the Internet to automate mundane tasks. The availability of portable, energy-efficient computing devices that can be easily integrated with clothing has renewed interest in the possibilities of wearware. The notion of a wearable network of interactive devices aiding users in their day-to-day activities is extremely appealing, but for it to become a reality researchers must develop interesting and useful applications. Consumers are not interested in the technology per se but in how it could enrich their lives.     

INVER2DBASE—A program to compute basement depths of density interfaces above which the density contrast varies with depth

A computer program to invert the gravity anomalies of density interfaces above which the density contrast varies with depth, is presented. The sediment–basement interface is approximated by an N-sided polygon. A function subprogram GR2DPOL and two subroutine subprograms ZOR2DPOL and SIMEQ support the main program. Subroutine ZOR2DPOL calculates the initial depth estimates of a density interface at all anomaly points on the principal profile using the infinite slab approximation. Function subprogram GR2DPOL computes the theoretical gravity anomaly of a density interface at each anomaly point on the profile and returns to the main program. Subroutine SIMEQ is used to solve n incremental depth parts of the vertices of a density interface. Partial derivatives are calculated by a simple finite-difference method. Normal equations are constructed and solved by Marquardt's algorithm. The proposed inversion scheme is independent on the equal station spacing criteria. The validity of the algorithm is demonstrated by calculating the basement depths of the Tucson basin, southern Arizona.     

Ion implantation studies on VOx films prepared by pulsed dc reactive sputtering

Vanadium oxide (VO_x) thin films find extensive use in room-temperature bolometers for IR imaging. It is desirable to control and modify the electronic properties of this temperature-sensitive material with treatments such as ion implantation and thermal annealing. In this work, we report on the modification of structural and electrical properties of VO_x thin films of varying compositions, deposited by pulsed dc reactive sputtering using a vanadium target under different oxygen flow rates. The as-deposited resistivities of the films ranged from 0.1 Ω cm to 100 Ω cm and the temperature coefficient of resistance (TCR) values varied from ?1.1% to ?2.7%. VO_x films used in microbolometers need to have a high TCR (>2%) and low resistivity values (1–10 Ω cm) in order to maximize sensitivity in conjunction with the read-out integrated circuit (ROIC). However, one usually finds a high TCR associated with high resistivity. Hence ion implantation followed by annealing was performed with the goal of improving the trade-off between TCR and resistivity. Two species – hydrogen (active) and helium (inert) – were chosen for implantation. Hydrogen is strongly electroactive and is well known for passivating defect states in a wide variety of electronic materials. As inert species, helium was chosen mainly to study the effects of bombardment on the film. The implanted films were annealed in an inert atmosphere to allow defect control and redistribution of atoms, and then characterized by current–voltage measurements over a wide temperature range. An order of magnitude change in resistance, and significant variations in TCR were observed. Further characterization has been done by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to correlate these resistivity changes with the structure of the films.     

Mathematical modelling of divided blast cupola

A pseudo 2-D mathematical model has been developed to simulate a cupola with one row and two rows of tuyère. The simulation results predicted higher spout temperature and combustion ratio for cupola with two rows of tuyère compared to that with one row. Further, the model has been used to study the effect of the distance of separation between the two rows of tuyère on cupola performance. The computed results shows that the spout temperature increases with tuyère level separation and attains the maximum at an optimum distance of separation between two rows of tuyère. Above the optimum, the spout temperature starts decreasing. The exit gas temperature and combustion ratio increases monotonously with the increase in tuyère level separation. These results agree well with the reported experimental observations. The mechanism behind the improved cupola performance with two rows of tuyère has been deduced from the computed temperature and composition profiles inside the cupola.     

Effectiveness of ampicillin and combination of penicillin and chloramphenicol in the treatment of pneumonias: randomized controlled trial

OBJECTIVE: To assess the effectiveness of ampicillin and a combination of benzyl penicillin and chloramphenicol in the treatment of pneumonias. DESIGN: Randomized controlled trial. SETTING: Tertiary care hospital. SUBJECTS: Patients 5 months to 4 years old with pneumonias of < 2 weeks duration. Exclusion criteria included acute bronchiolitis, allergy to penicillin, postmeasles pneumonia or prior administration of trial antibiotics in full dose for more than 2 days. INTERVENTION: Patients were randomized to receive either ampicillin (100 mg/kg/day) or combination of benzyl penicillin (100,000 units/kg/day) and chloramphenicol (100 mg/kg/day). The outcome measure was cure rate. RESULTS: There were 52 and 49 patients in the ampicillin and the combination groups, respectively. There was no significant difference in the baseline characteristics between groups except, nasal flare and cyanosis which were less in benzyl penicillin plus chloramphenicol group. There was also no difference either in the primary outcome, cure rate or secondary outcomes (days for cure, duration of tachypnea, fever and grunt) in the two. CONCLUSION: Considering the potential toxicity of chloramphenicol and the number of injections and doses to be given for the combination, ampicillin as a single drug could be preferred for the treatment of pneumonias, in this part of the country.     

Prioritizing Structural Management by Quantifying the Effect of Land Use and Land Cover on Watershed Runoff and Sediment Yield

Hydrological processes in a mixed land use watershed are significantly influenced by land use (LU) and land cover (LC). In order to quantify the effect of LU/LC, topography, and morphology, runoff and sediment yield of a small multivegetated watershed in a sub-humid subtropical region in India were simulated by the Soil and Water Assessment Tool (SWAT) model and were compared with measured values. The mixed land use watershed displayed a synchronized runoff response to monsoon rains. Measured runoff and sediment yield varied one sub-watershed to another and ranged, respectively, from 256.33 to 367.83 mm and from 0.27 to 11.65 t/ha for 734.90 mm of rainfall in 2000 and from 310.36 to 393.49 mm and from 0.84 to 10.71 t/ha for 765.50 mm of rainfall in 2001. The correlation coefficient between rainfall and runoff was 0.86, that between runoff and sediment yield was 0.56, and that between rainfall and sediment yield was 0.55. The sub-watersheds with relatively high forest cover (SWS1 and SWS2) showed significantly less runoff and sediment yield (310.36 mm and 0.84 t/ha), whereas a sub-watershed with more area under cultivation produced higher runoff (393.5 mm) and higher sediment yield (11.65 t/ha). Measured and model simulated estimates of runoff and sediment yield from different sub-watersheds were employed to prioritize control measures in the watershed comprising areas under cultivation, waste, fallow and eroded land, and forest and bushes. The average estimates of sediment yield from different sub-watersheds were used to prioritize the checkdam construction as an effective measure to control sediment transport to downstream water resources.