Narrow Results

This paper contains natural convection of Ag–MgO/water micropolar hybrid nanofluid in a hollow hot square enclosure equipped by four cold obstacles on the walls. The simulations were performed by the lattice Boltzmann method (LBM). The influences of Rayleigh number and volume fraction of nanoparticle on the fluid flow and heat transfer performance were studied. Moreover, the effects of some geometric parameters, such as cold obstacle height and aspect ratio, were also considered in this study. The results showed that when the aspect ratio is not large ($\mathrm{\text{AR}}=0.2$ or 0.4), at low Rayleigh number (10³), the two secondary vortices are established in each main vortex and this kind of secondary vortex does not form at high Rayleigh number (10⁶). However, at $\mathrm{\text{Ra}}=10^6$, these secondary vortices occur again in the middle two vortices at $\mathrm{\text{AR}}=0.6$, which is similar to that at $\mathrm{\text{Ra}}=10^3$. At $\mathrm{\text{AR}}=0.2$, the critical Rayleigh number, when the dominated mechanism of heat transfer changes from conduction to convection, is 10⁴. However, the critical Rayleigh number becomes 10⁵ at $\mathrm{\text{AR}}=0.4$ or 0.6. When the cold obstacle height increases, the shape of the vortices inside the enclosure changes due to the different spaces. Besides, at $\mathrm{\text{Ra}}=10^6$, for different cold obstacle heights, the location of the thermal plume is different, owing to the different shapes of vortices. Accordingly, the average Nusselt number increases by increment of the Rayleigh number, nanoparticle volume fraction, cold obstacle height and aspect ratio.

The micromixer is an important prerequisite for realizing the function of the microfluidic chip system. Micromixers are mainly used in protein crystallization, biological reactions, drug delivery and other fields. Efficient micromixers enable fast bioreaction processes. In this paper, according to the principle of plane geometry, micromixers with three different structural obstacles, circular, equilateral triangle and square, are designed to study how to improve the mixing efficiency of the micromixer. In this paper, the influence of the obstacle structure on the mixing efficiency and pressure drop of the micromixer is analyzed. Through numerical simulation, the results show that when Re = 100, the mixing efficiency of the circular obstacle micromixer is up to 97.4%, and the pressure drop is 15,789.597 Pa. In addition, this paper analyzes that the use of cylindrical obstacles can make the fluid generate horizontal and vertical vortex flow, break the usual laminar flow, and significantly improve the mixing efficiency.

A Glimpse into Healthcare Policies: How Cancer Control and Prevention Programmes Have Evolved Across Asia.

Understanding Healthcare Policies in the Philippines: Cancer Care.

Healthcare Systems and Health Policies in Thailand: Cancer Care.

Cancer Care and Control in Taiwan: An Interview with Dr. Shu-Ti Chiou.

An Interview with Professor Myint Han: Healthcare in Myanmar.

Development processes in which software is integrated in hardware products are explored with the aim of finding obstacles to the development process and hypothesising how they can be dealt with. Empirical data are based on case studies in nine manufacturing companies chosen to have a varied amount of software in their products and experience of technology integration. Results indicate that obstacles in experienced companies concern processes, structures and resources but few culture-related issues. In companies with short experience of software integration in hardware development, cultural aspects were important. Where new technology played a strategic role in the product function, organisational issues such as structures, processes and cultural differences formed obstacles. Where technology only had a supporting role, resource-related obstacles such as lack of competencies were more important. Managerial measures tended to be partly related to the different types of obstacles, partly to the strategic situation of the company.

Achieving effective innovation is a complex task and during this process, firms [especially small and medium sized enterprises (SMEs)] often face obstacles. However, research into obstacles to innovation focusing on SMEs is very scarce. In this study, we propose a theoretical framework for describing these obstacles to innovation and investigate their influence on the innovative performance of SMEs. Data were collected in 2013 through face-to-face interviews with executives of 49 technology SMEs from Germany. The semi-structured interviews were designed on the basis of scales for measuring innovativeness, financial/competitive performance and obstacles to innovation, next to purely open questions. We find that the internal obstacles, lack of know-how, capacity overloading, unclear roles and tasks as well as the external obstacle governmental bureaucracy negatively influence innovative performance of SMEs. However, in contrast to prior findings, this study shows that cooperation ties of firms might also negatively influence the innovative performance.

A better understanding of the kinematics and control strategies adopted during obstacle crossing is essential for the prevention of injuries associated with falls in the elderly. The effects of obstacle height on the foot clearance, foot-obstacle distance and joint kinematics have presented significant controversy. This may be related to the selection of obstacle height, whether the obstacles are normalized to the leg length, and to the calculation of the foot-obstacle clearance, as well as the extraction of representative joint angles for the analysis. In this study, fourteen young healthy adults wearing 28 infrared retroreflective markers walked and crossed obstacles of heights of 0%, 10%, 20% and 30% of their leg lengths in a gait laboratory equipped with a 3D motion analysis system. Three-dimensional joint kinematics of the lower limb were calculated. Foot clearances were calculated using the heel and toe markers. The results suggested that young subjects maintained a constant margin of leading foot clearance when crossing higher obstacles (higher than 79.4mm) and a constant trailing foot clearance for all obstacle heights. Both toe-obstacle and heel-obstacle horizontal distances were not affected by obstacle height. Apart from the peak values, kinematic variables for the leading limb should be considered both when the toe and heel cross the obstacle while only those when the toe crosses the obstacle for the trailing limb. Not only in the sagittal plane, motions of the lower limb in the other two planes were also important when investigating the kinematics of the leading limb during obstacle crossing. The present study clarified some of the controversies in the literature of obstacle-crossing through careful comparisons of kinematic variables obtained from different study aspects. The results will be helpful for future studies to gain insight into the kinematics and control strategies adopted during obstacle-crossing.

This paper develops the results of works Refs. 1–4. Methods for designing of insectomorphic six-legged robot motion to overcome complicated obstacles by means of Coulomb friction are presented. Those obstacles are two identical lofty horizontal shelves connected by a narrow horizontal beam, a ladder leaned against a vertical wall of the shelf and a ball which can roll along a horizontal plane. The 3D computer simulation was fulfilled to demonstrate effectiveness and robustness of elaborated methods for obstacles overcoming.

The study firstly addressed the dynamics of droplets during passive micromixing program using obstacles and porous media by modified lattice Boltzmann method (LBM). The modified Shan-Chen model was introduced in LBM. The simulation results show that, the inlet velocity plays a more important role in the coalescence length than the size of obstacle when droplet passing a cylinder at the microscale. There exists a critical obstacle size, beyond which the big obstacle is unfavorable to generating small droplets. The metal foam is more beneficial to generating smaller droplets than obstacle at the microscale. Big PPI is favorable to the formation of small droplets. The simulation results indicate the great potential of metal foam in generating smaller droplets because its porous stricture effectively reduce the second coalescence of broken droplets.