Traction-energy balancing adaptive control with slip optimization for wheeled robots on rough terrain

On rough terrain, excessive wheel slippage is easily generated by changes of surface conditions such as soil types and geometries. It induces considerable loss of wheel traction and battery energy. To prevent this, wheeled robots should consistently recognize the current situation generated between wheel and surface. And also wheeled robots are required to optimally control wheel motion in limited wheel traction and battery capacity. Therefore, this paper proposes a novel wheel control algorithm based on slip optimization of traction and energy, which is adaptive to change of surface condition. Proposed wheel control algorithm is called Traction-Energy Balancing Adaptive Control (TEB) in this paper and TEB assigns optimized rotation speed to each wheel by observing wheel slip ratio which is a key parameter of TEB. As functions of TEB, TEB is largely divided into three main parts; (1) slip optimizer (2) slip controller (3) SC-compensator. In the slip optimizer, two optimal slip models were derived as a function of slip ratios regarding maximum traction and tractive efficiency using experimental data about wheel-terrain interaction in three types of soil (grass, gravel and sand). And the optimal slip models were employed in order to determine a desired slip value of wheel with observation of a change in actual robot velocity as control input in the slip controller. For optimal slip control, the proposed slip controller is based on conventional PID controller with compensating disturbance in the controller (SC-compensator) which occurs by change of surface shapes. In the SC-compensator, radial function networks (RBFN) was applied in the slip controller and RBFN was of help to readjust previously set PID gains depending on occurred slip error. Finally, TEB was experimentally verified by controlling a real robot having four wheels on various terrain types.     

CROSSING THE DIVIDE: LESSONS FROM DEVELOPING WIND ENERGY IN POST‐FACT AMERICA

The income and careers that come with building wind turbines have become a lifeline for many factory towns and farming communities. Generating electricity from the wind puts increasingly cheap power on the grid, saving consumers billions a year. And it is one of the biggest, fastest, cheapest ways to reduce carbon pollution, reducing the threat of climate change. Yet as wind farms have rapidly spread to forty‐one states, their developers must make their case anew with each community that hosts them. Facts matter, but so do empathy, honoring deep connections to neighbors and landscape, and developing mutual respect. Successful wind farm developers listen first for shared values and speak with inclusive language, to communicate with potential opponents across divides of misunderstanding and motivate local residents to adapt to and benefit from change.     

CAN SCIENCE AND RELIGION RESPOND TO CLIMATE CHANGE?

With the challenge of communicating climate science in the United States and making progress in international negotiations on climate change there is a need for other approaches. The moral issues of ecological degradation and climate justice need to be integrated into social consciousness, political legislation, and climate treaties. Both science and religion can contribute to this integration with differentiated language but shared purpose. Recognizing the limits of both science and religion is critical to finding a way forward for addressing the critical challenges of climate change. How we value nature and human–Earth relations is crucial to this. We need a broader environmental ethics in dialogue with the science of climate change.     

‘Age-hardened alloy’ based on bulk polycrystalline oxide ceramic

We report here for the first time the development of ‘age-hardened/toughened’ ceramic alloy based on MgO in the bulk polycrystalline form. This route allows for the facile development of a ‘near-ideal’ microstructure characterized by the presence of nanosized and uniformly dispersed second-phase particles (MgFe₂O₄) within the matrix grains, as well as along the matrix grain boundaries, in a controlled manner. Furthermore, the intragranular second-phase particles are rendered coherent with the matrix (MgO). Development of such microstructural features for two-phase bulk polycrystalline ceramics is extremely challenging following the powder metallurgical route usually adopted for the development of bulk ceramic nanocomposites. Furthermore, unlike for the case of ceramic nanocomposites, the route adopted here does not necessitate the usage of nano-powder, pressure/electric field-assisted sintering techniques and inert/reducing atmosphere. The as-developed bulk polycrystalline MgO–MgFe₂O₄ alloys possess considerably improved hardness (by ~52%) and indentation toughness (by ~35%), as compared to phase pure MgO.     

High-pressure torsion of metastable austenitic stainless steel at moderate temperatures

We subjected samples of a 304 metastable austenitic stainless steel to high-pressure torsion (HPT) in the temperature range of 303–573 K, (i.e. at different austenite stabilities), to examine their microstructures and mechanical properties. HPT processing at room temperature led to the formation of a lamellar microstructure with austenitic and martensitic phases, of which sizes were characterised by prior austenite grains, whereas HPT processing at moderate temperatures produced nanostructured austenite grains through mechanical twinning. The nanostructured 304 steel with an average grain size of ~70 nm exhibited a fine balance between tensile strength (~1.7 GPa) and reduction of area (~55%).     

Aesthetics and Affect: Engaging Energy Communities

ABSTRACT

Engaging publics in participatory events has become a central means to introducing lay people's voices into processes of technoscientific innovation and governance. However, little attention has been paid to the role of aesthetics, especially in terms of opening up potential ways of critically and creatively engaging with technoscientific matters of concern. The terms semblamatic and matters of potentially are proposed as addressing this dimension of aesthetics. Drawing on practice-based design research, a probe workshop with members of energy communities was implemented. Three probe exercises served to open up potential re-articulations of such core themes as energy, communities and futures. Our goals were to examine the whether such probes enabled semblamatic responses and the emergence of matters of potentiality. Findings were mixed. The continued retention of standard meanings of these core themes suggested that such events can be anaesthetic, blunting access to the semblamatic aspects of engagement. Conversely, there was some opening up in which the core themes were creatively re-articulated. The present perspective, with its three novel terms - semblamatic, matters of potentiality, and anaesthetic - might prove useful in alerting scholars to the complex role of aesthetics in the methodological and analytic practices entailed in engagement with publics.     

Influence of properties of layered silicate minerals on adsorbed DNA surface affinity,self-assembly and nanopatterning

We report on the specific interaction between DNA and some mica-family minerals and other layered silicate structures. The interaction depends on mineral surface's crystallography, chemistry and potential. These properties are responsible for a remarkable variety of adsorption mechanisms and can be used to modulate surface self-assembly and nanopatterning of DNA. The controlled deposition of DNA onto non-conductive mineral regions with atomically flat boundaries has very attractive applications in nano-biotechnology (for example, microelectronics, microarrays and sensors). In addition, the extreme affinity discovered for some mineral surfaces, together with their ability to organize the DNA molecules, could be an indication of their catalytic potential. It may also have had relevance in the prebiotic environment, with important implications for the earth and life sciences.     

Understanding scale-dependent yield stress of metals at micrometre scales

The mechanical softening behaviour of micrometre-scale metals (free-standing metal foils and wires) with decreasing either the geometrical or the microstructural scale (i.e. the smaller, the weaker) has recently been reported. Here, we present a mechanism-based model to understand the softening behaviour, which is based on competition between the effects of surface grain relaxation and the interior grain strengthening effect. The model describes well the yield stress of Cu foils with different ratios of the thickness to grain size.     

重新认识心衰机制中的心脏舒张期耗能

长期以来,对心衰和心衰机制的认识一直存在争议,所以心衰的治疗一直是国内外心血管领域中的一个挑战.为了澄清心衰机制的内涵,本文用弗兰克-斯塔灵定律以及能量守恒定律作为重建心脏理论以及心衰机制的依据,论证了心脏的做功是从动能向势能,又从势能向动能的转换过程.并根据临床事实等来证实心脏舒张是在作功,与收缩期作功是等同的.没有心脏的舒张就没有心脏的收缩,心脏功能下降实际上是舒张与收缩功能同时的下降.不存在有收缩功能正常的舒张功能下降.心功能的判定标准不能采用射血分数,而应该采取能量消耗的定量方法来测定.     

Learning to Minimize Energy Costs and Maximize Mechanical Work in a Bimanual Coordination Task

The authors addressed the hypothesis that economy in motor coordination is a learning phenomenon realized by both reduced energy cost for a given workload and more external work at the same prepractice metabolic and attentional energy expenditure. "Self-optimization" of movement parameters has been proposed to reflect learned motor adaptations that minimize energy costs. Twelve men aged 22.3 ± 3.9 years practiced a 90° relative phase, upper limb, independent ergometer cycling task at 60 rpm, followed by a transfer test of unpracticed (45 and 75 rpm) and selfpaced cadences. Performance in all conditions was initially unstable, inaccurate, and relatively high in both metabolic and attentional energy costs. With practice, coordinative stability increased, more work was performed for the same metabolic and attentional costs, and the same work was done at a reduced energy cost. Selfpaced cycling was initially below the metabolically optimal, but following practice at 60 rpm was closer to optimal cadence. Given the many behavioral options of the motor system in meeting a variety of everyday movement task goals, optimal metabolic and attentional energy criteria may provide a solution to the problem of selecting the most adaptive coordination and control parameters.