Two decoupled antennas, comprising two feeding monopoles and one dipole shared by the monopoles, for the fifth‐generation (5G) multi‐input multi‐output (MIMO) applications are proposed. The feeding ...monopoles are placed on both sides of the coupled‐fed, common dipole. First, to operate in the 3.3–5.0 GHz 5G wideband, two resonant modes at about 3.6 and 4.7 GHz, contributed to by the common dipole and the feeding monopoles respectively, are utilized. Then, by introducing distributed capacitance loaded on the dipole center, the one‐wavelength dipole resonant mode can be lowered to oppose the counter‐phased half‐wavelength mode currents on the half dipole, resulting in self decoupling around 3.6 GHz. The mutual coupling for the common dipole is reduced by about 19 dB in this study. The design shows a small size of 35 mm × 5 mm (0.38‐wavelength × 0.05‐wavelength at 3.3 GHz) and can be a promising candidate for narrow‐bezel 5G laptop computers.
•A wearable RGB-D camera based indoor navigation system for the blind is proposed.•Egomotion estimation is performed using both sparse features and dense point clouds.•Probabilistic mapping and ...traversability analysis for path planning is presented.•The system stores and reloads maps to expand coverage area of navigation.•The system improves mobility performance complementing the white cane.
In this paper, a novel wearable RGB-D camera based indoor navigation system for the visually impaired is presented. The system guides the visually impaired user from one location to another location without a prior map or GPS information. Accurate real-time egomotion estimation, mapping, and path planning in the presence of obstacles are essential for such a system. We perform real-time 6-DOF egomotion estimation using sparse visual features, dense point clouds, and the ground plane to reduce drift from a head-mounted RGB-D camera. The system also builds 2D probabilistic occupancy grid map for efficient traversability analysis which is a basis for dynamic path planning and obstacle avoidance. The system can store and reload maps generated by the system while traveling and continually expand the coverage area of navigation. Next, the shortest path between the start location to destination is generated. The system generates a safe and efficient way point based on the traversability analysis result and the shortest path and updates the way point while a user is constantly moving. Appropriate cues are generated and delivered to a tactile feedback system to guide the visually impaired user to the way point. The proposed wearable system prototype is composed of multiple modules including a head-mounted RGB-D camera, standard laptop that runs a navigation software, smart phone user interface, and haptic feedback vest. The proposed system achieves real-time navigation performance at 28.6Hz in average on a laptop, and helps the visually impaired extends the range of their activities and improve the orientation and mobility performance in a cluttered environment. We have evaluated the performance of the proposed system in mapping and localization with blind-folded and the visually impaired subjects. The mobility experiment results show that navigation in indoor environments with the proposed system avoids collisions successfully and improves mobility performance of the user compared to conventional and state-of-the-art mobility aid devices.
Taking notes on laptops rather than in longhand is increasingly common. Many researchers have suggested that laptop note taking is less effective than longhand note taking for learning. Prior studies ...have primarily focused on students' capacity for multitasking and distraction when using laptops. The present research suggests that even when laptops are used solely to take notes, they may still be impairing learning because their use results in shallower processing. In three studies, we found that students who took notes on laptops performed worse on conceptual questions than students who took notes longhand. We show that whereas taking more notes can be beneficial, laptop note takers' tendency to transcribe lectures verbatim rather than processing information and reframing it in their own words is detrimental to learning.
In this study, a compact (15 mm × 12 mm) uniplanar multi-band antenna is proposed for laptops and tablets application with a near omni-directional coverage. The main structure of the antenna ...implements meander design for compactness and multi-band operation. A staircase-type arm and an F-shaped arm are added for achieving resonances at exact frequencies and for good impedance matching, respectively. The antenna is designed such that it operates in all the global positioning system/wireless local area network/worldwide interoperability for microwave access bands and is easy to fabricate and integrate inside laptops/tablets. A prototype of the proposed antenna is fabricated, and its performance is validated for multi-band operation and omni-directional radiation.
We all make use of oxide ultrathin films, even if we are unaware of doing so. They are essential components of many common devices, such as mobile phones and laptops. The films in these ubiquitous ...electronics are composed of silicon dioxide, an unsurpassed material in the design of transistors. But oxide films at the nanoscale (typically just 10 nm or less in thickness) are integral to many other applications. In some cases, they form under normal reactive conditions and confer new properties to a material: one example is the corrosion protection of stainless steel, which is the result of a passive film. A new generation of devices for energy production and communications technology, such as ferroelectric ultrathin film capacitors, tunneling magnetoresistance sensors, solar energy materials, solid oxide fuel cells, and many others, are being specifically designed to exploit the unusual properties afforded by reduced oxide thickness. Oxide ultrathin films also have tremendous potential in chemistry, representing a rich new source of catalytic materials. About 20 years ago, researchers began to prepare model systems of truly heterogeneous catalysts based on thin oxide layers grown on single crystals of metal. Only recently, however, was it realized that these systems may behave quite differently from their corresponding bulk oxides. One of the phenomena uncovered is the occurrence of a spontaneous charge transfer from the metal support to an adsorbed species through the thin insulating layer (or vice versa). The importance of this property is clear: conceptually, the activation and bond breaking of adsorbed molecules begin with precisely the same process, electron transfer into an antibonding orbital. But electron transfer can also be harnessed to make a supported metal particle more chemically active, increase its adhesion energy, or change its shape. Most importantly, the basic principles underlying electron transfer and other phenomena (such as structural flexibility, electronic modifications, and nanoporosity) are now largely understood, thus paving the way for the rational design of new catalytic systems based on oxide ultrathin films. Many of the mechanisms involved (electron tunneling, work function changes, defects engineering, and so forth) are typical of semiconductor physics and allow a direct link between the two fields. A related conceptual framework, the “electronic theory of catalysis”, was proposed a long time ago but has been largely neglected by the catalytic community. A renewed appreciation of this catalytic framework, together with spectacular advances in modeling and electronic structure methods, now makes it possible to combine theory with advanced experimental setups and meet the challenge of designing new materials with tailored properties. In this Account, we discuss some of the recent advances with nanoscale oxide films, highlighting contributions from our laboratory. Once mastered, ultrathin oxide films on metals will provide vast and unforeseen opportunities in heterogeneous catalysis as well as in other fields of science and technology.
This paper explores the relationship of subject areas to teachers' technology integration. Educational technology research has often identified 'culture clashes' to explain differences in technology ...use between subject areas. These clashes are frequently attributed to core features, values and beliefs held in the subject area cultures, but there has been little research analyzing the relationship between subject areas and integration. Using a validated path model as a conceptual framework, this paper presents an analysis of the relationship between three subject areas (English, Mathematics, Science) and known factors of teacher beliefs and readiness to use technology in teaching, which directly impact on secondary-level teachers' technology integration, over three years. Findings show that time and subject areas are both associated with teachers' readiness, but only subject areas are associated with teachers' beliefs. Implications for practice and future research are discussed. Author abstract
•A dual-evaporator ultra-thin loop heat pipe of 1 mm thickness has been proposed.•A novel multi-heat source cooling solution for laptops.•The maximum heat load can be reached 22 W–22 W.•Different ...heat loads increase heat leak and thus reduces heat transfer performance.
The thermal management of laptops is challenged by the presence of multiple heat sources with non-uniform distribution and limited space for heat dissipation. This paper proposes the application of a 1 mm thickness dual-evaporator ultra-thin loop heat pipe (DE-UTLHP) for cooling laptops. The start-up performance and steady-state heat transfer performance of the dual-evaporator ultra-thin loop heat pipes were studied under equal or unequal heat loads. The results show that successful set-up can be achieved within the range of heat loads from 5 W–5 W to 20 W–20 W in the horizontal orientation. And it can achieve a maximum heat load of up to 22 W–22 W and a minimum thermal resistance of 0.69 °C/W. Furthermore, it was found that it exhibited better heat transfer performance in the vertical orientation compared to the horizontal orientation. The proposed dual-evaporator ultra-thin loop heat pipes can convert isolated and dispersed direct heat dissipation into centralized and integrated thermal management for future laptops.
Consumers use warmth and competence, two fundamental dimensions that govern social judgments of people, to form perceptions of firms. Three experiments showed that consumers perceive nonprofits as ...being warmer than for‐profits but as less competent. Further, consumers are less willing to buy a product made by a nonprofit than a for‐profit because of their perception that the firm lacks competence. Consequently, when perceived competence of a nonprofit is boosted through subtle cues that connote credibility, discrepancies in willingness to buy disappear. In fact, when consumers perceive high levels of competence and warmth, they feel admiration for the firm—which translates to consumers’ increased desire to buy. This work highlights the importance of consumer stereotypes about nonprofit and for‐profit companies that, at baseline, come with opposing advantages and disadvantages but that can be altered.
We present the first fast and detailed computation of the cosmological recombination radiation released during the hydrogen (redshift z ... 1300) and helium (z ... 2500 and 6000) recombination ...epochs, introducing the code COSMOSPEC. Our computations include important radiative transfer effects, 500-shell bound-bound and free-bound emission for all three species, the effects of electron scattering and free-free absorption as well as interspecies (HeII...HeI...HI) photon feedback. The latter effect modifies the shape and amplitude of the recombination radiation and COSMOSPEC improves significantly over previous treatments of it. Utilizing effective multilevel atom and conductance approaches, one calculation takes only ...15 s on a standard laptop as opposed to days for previous computations. This is an important step towards detailed forecasts and feasibility studies considering the detection of the cosmological recombination lines and what one may hope to learn from the ...6.1 photons emitted per hydrogen atom in the three recombination eras. We briefly illustrate some of the parameter dependences and discuss remaining uncertainties in particular related to collisional processes and the neutral helium atom model. (ProQuest: ... denotes formulae/symbols omitted.)
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