Controlled growth of SnO₂@Fe₂O₃ double-sided nanocombs as anodes for lithium-ion batteries

A novel heterostructure is developed by grafting 1D SnO(2) nanorods onto both sides of pre-grown 2D Fe(2)O(3) nanoflakes, forming a comb-like rather than tree-like branched nanostructure. The SnO(2) nanorod branches are determined to grow along the [001] direction on the (±001) planes of Fe(2)O(3) nanoflakes. The resulting SnO(2)@Fe(2)O(3) nanocombs show stabilized cycling performance and improved volumetric energy density compared to pristine Fe(2)O(3) nanoflakes presumably due to the integration of SnO(2) branches as well as the 3D hierarchical structural features.     

The use of a double heat pipe heat exchanger system for reducing energy consumption of treating ventilation air in an operating theatre—A full year energy consumption model simulation

In two earlier papers [Y.H. Yau, Application of a heat pipe heat exchanger to dehumidification enhancement in tropical HVAC systems—a baseline performance characteristics study, International Journal of Thermal Sciences 46 (2) (2007) 164–171; Y.H. Yau, The analysis of enthalpy change with and without a heat pipe heat exchanger in a tropical air conditioning system, International Journal of Energy Research 30 (15) (2006) 1251–1263], two series of experiments were conducted under controlled conditions to establish the baseline performance characteristics of the heat pipe heat exchanger (HPHX). In the present paper, a complete empirical transient systems simulation program model is assembled to estimate the air states as well as the entire typical meteorological year energy consumption of an operating theatre located in Kuala Lumpur, Malaysia.     

Application control chart concepts of designing a pre-alarm system in the nuclear power plant control room

This study applied the concepts of the Shewhart control chart to design a pre-alarm system for the nuclear power plant control room. As a support in detecting faults, the pre-alarm system reminded the operators of a change in the system state in its early stages. Two pre-alarm types were designed to compare with the original system, and all participants were requested to monitor each simulated system under both normal and abnormal states. The tasks for the participants included shutting down the reactor, searching for procedures, monitoring system parameters and executing secondary tasks. In each trial, the task performance, mental workload and situation awareness (SA) of the participants were measured. Results indicated that participants had lower mental workload, but equal SA, when monitoring the system with either type of pre-alarm designs, and lower alarm frequency and higher secondary task performance were obtained with the pre-alarm design. Therefore, the pre-alarm system effectively assisted the operators in monitoring tasks.     

New Failure Load Criterion for Large Diameter Bored Piles in Weathered Geomaterials

In the literature, various “failure criteria” or methods of estimating the failure load in pile loading tests have been proposed. The criteria, based on varying assumptions, were intended for different methods of pile testing and were verified on tests of a variety of pile types and sizes. Most of the criteria were not developed for slow maintained loading tests of large-diameter (greater than 0.6 m) and long bored piles. Piles of this kind have considerable resistance, and it is often impractical to reach failure load as defined by the various criteria. In this paper, a total of 38 large-diameter bored piles (drilled shafts) that were tested, ranging from 0.6 to 1.8 m in diameter, varying from 12 to 66 m in depth, and founded in weathered geomaterials (rocks and saprolites), are critically reviewed and studied. Among them, a selection of seven pile load tests is examined in detail by using different existing failure criteria and specifications. The tests were chosen for their high degree of mobilization of pile capacity and the availability of reliable load-movement relationships. Specific aspects of pile behavior, such as the mobilization of toe resistance and shaft shortening, are also investigated using 31 loading tests to develop a new failure load criterion. The writers were heavily involved with the construction, testing, and analysis of 15 of the 38 piles. From the results of the study, a new nonsubjective, semiempirical method is proposed for estimating the approximate interpreted failure loads for piles founded in weathered geomaterials. The method is based on a moderately conservative estimation of the movement required to mobilize toe resistance and incorporates observations of shaft shortening from pile loading tests. Generally, the new method may allow more effective and consistent designs for large-diameter bored piles in weathered geomaterials.     

ML and REML estimation in survival analysis with time dependent correlated frailty

In the study of multiple failure times for the same subjects, for example, recurrent infections for patients with a given disease, there are often subject effects, that is, subjects have different risks that cannot be explained by known covariates. Standard methods, which ignore subject effects, lead to overestimation of precision. The frailty model for subject effects is better, but can be insufficient, because it assumes that subject effects are constant over time. Experience has shown that the dependence between different time periods often decreases with distance in time. Such a model is presented here, assuming that the frailty is no longer constant, but time varying, with one value for each spell. The main example is a first-order autoregressive process. This is applied to a data set of 128 patients with chronic granulomatous disease (CGD), participating in a placebo controlled randomized trial of gamma interferon (gamma-IFN), suffering between 0 and 7 infections. It is shown that the time varying frailty model gives a significantly better fit than the constant frailty model.     

Numerical analysis of travelling wave structure using hybrid basisfunctions in the method of moments

A new model is presented to improve the computational efficiency of analysing large travelling wave antennas: such as leaky wave antennas using the method of moments (MoM). The method uses a new type of travelling wave basis function which interfaces seamlessly with the rooftop sub-domain basis function. The computation time and resources are significantly economised by reducing the size of the matrix     

On the ‘excess white noise’ in MOS transistors

Special silicon MOS transistors are fabricated to demonstrate that the proposed ‘excess white noise’ attributed to the mobility fluctuation does not exist. The previously observed excess noise over the white thermal noise is shown to be caused by a 1/f-type noise component due to noise measurements at insufficiently high frequencies on devices which have very high 1/f noise.     

Reverse engineering of complex geometry using rational B-splines

Rational B-splines have become the new standard for representing free-form curves and surfaces. This paper presents a method for approximating rational B-splines using digitised data. Instead of using the classical optimisation approach to solve the multivariable nonlinear equations, a new method based on iterations of least-squares solutions and single variable mimimisation is developed. This is made possible by modifying the original objective function to avoid the rational format. Simulation of fitting a 90° arc shows that the algorithm can produce accurate solutions close to nominal values. The efficiency of the algorithm also makes it possible to apply the method to day-to-day reverse engineering problems using rational B-splines.     

A performance‐based bridge LCCA model using visual inspection inventory data

Since most bridge life cycle cost analysis (LCCA) depends heavily on the analyst's experience to determine the times and costs of remedial actions over a bridge's lifetime, the results are often subject to question because of their subjectivity. While some work has been done over the years to develop reliable deterioration models for determining such times and costs, the proposed models often require sophisticated inspection data, which is costly to obtain, and/or complex mathematical calculations. A simple linear deterioration model based on visual inspection inventory data concerning bridge components is introduced and integrated into the LCC analysis. The proposed model provides an alternative approach to bridge LCC analysis that can improve the objectivity of analysis and does not require input of sophisticated inspection, and thus facilitates application of bridge life cycle cost analysis. The LCCA method developed in this study is applied to a case study of alternative PCI (Pre‐stressed Concrete I‐girder) and a PCB (Pre‐stressed Concrete Box‐girder) bridges for the purpose of model validation.