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ISOFF Vacuumatic Concrete: From Boats to Architecture
No full textAbstract With the invention of ferro-cement by Jean Louis Lambot around 1848, a new material and corresponding manufacturing technique had been introduced for producing structural objects with beneficial material properties (light-weight, strong, ductile and watertight), great formability potential and ease of construction. Although this 'new' material had first been applied to relatively small-scale structural objects, such as rowing boats, the technology got successfully adopted in the field of architecture. Pier Luigi Nervi, amongst others, is worldly renowned for using ferro-cement as a permanent formwork for realising appealing, yet structurally efficient (ribbed) floor and structures. In the same tradition as the early applications of ferro-cement, this paper introduces a 'new' material and corresponding manufacturing technique, referred to as 'Vacuumatic Concrete', of which its potential is demonstrated by producing a small boat (or rather canoe). Further developments are mainly focussed on architectural applications. Research on Vacuumatics 3D Formwork Systems by the first author has put forward the idea of effectively using vacuum pressure to draw a concrete mortar with low viscosity through a porous material, analogue to the resin-infusion process that is used for producing light-weight composite structures (not-surprisingly also boat hulls). Instead of applying the technique to an aggregate core, the intention of this study has been to use a sheet of spacer material, which is intended not only to function as a flow medium for the concrete mortar, but also as the reinforcement of the concrete object when fully cured. Ideally, the vacuum-infusion process facilitates the casting process of the concrete mortar as it does not require the use of (potentially) complex, double-faced, rigid formworks
Red leaf margins indicate increased polygodial content and function as visual signals to reduce herbivory in Pseudowintera colorata
No full textSummary • Red-pigmented leaf margins are common, but their functional significance is unknown. We hypothesized that red leaf margins reduce leaf herbivory by signalling to herbivorous insects the presence of increased chemical defences. • Leaves were collected from a natural population of Pseudowintera colorata. Margin size, herbivory damage, anthocyanin content and concentrations of polygodial, a sesquiterpene dialdehyde with antifeedant properties, were quantified. Feeding trials involving larvae of Ctenopseustis obliquana, a generalist herbivore, were conducted on red-and green-margined P. colorata leaves in darkness, or under white, green or red light. • Leaves with wider red margins contained higher concentrations of polygodial and anthocyanins, and incurred less natural herbivory. In trials under white light, C. obliquana consumed disproportionately more green-than red-margined leaf laminae. Larvae exhibited no feeding preference when light was manipulated such that leaf colour discrimination was impaired. • Red leaf margins provide a reliable and effective visual signal of chemical defence in P. colorata. Ctenopseustis obliquana larvae perceive and respond to the colour of the leaf margins, rather than to olfactory signals. Our study provides direct experimental evidence for aposematic coloration in red leaves
A 27-mW CMOS Fractional- Synthesizer Using Digital Compensation for 2.5-Mb/s GFSK Modulation
No full textAbstract-A digital compensation method and key circuits are presented that allow fractional-N synthesizers to be modulated at data rates greatly exceeding their bandwidth. Using this technique, a 1.8-GHz transmitter capable of digital frequency modulation at 2.5 Mb/s can be achieved with only two components: a frequency synthesizer and a digital transmit filter. A prototype transmitter was constructed to provide proof of concept of the method; its primary component is a custom fractional-N synthesizer fabricated in a 0.6-m CMOS process that consumes 27 mW. Key circuits on the custom IC are an onchip loop filter that requires no tuning or external components, a digital MASH 6-1 modulator that achieves low power operation through pipelining, and an asynchronous, 64-modulus divider (prescaler). Measurements from the prototype indicate that it meets performance requirements of the digital enhanced cordless telecommunications (DECT) standard
Emergence of a Snake-Like Structure in Mobile Distributed Agents: An Exploratory Agent-Based Modeling Approach
No full textThe body structure of snakes is composed of numerous natural components thereby making it resilient, flexible, adaptive, and dynamic. In contrast, current computer animations as well as physical implementations of snake-like autonomous structures are typically designed to use either a single or a relatively smaller number of components. As a result, not only these artificial structures are constrained by the dimensions of the constituent components but often also require relatively more computationally intensive algorithms to model and animate. Still, these animations often lack life-like resilience and adaptation. This paper presents a solution to the problem of modeling snake-like structures by proposing an agent-based, self-organizing algorithm resulting in an emergent and surprisingly resilient dynamic structure involving a minimal of interagent communication. Extensive simulation experiments demonstrate the effectiveness as well as resilience of the proposed approach. The ideas originating from the proposed algorithm can not only be used for developing self-organizing animations but can also have practical applications such as in the form of complex, autonomous, evolvable robots with self-organizing, mobile components with minimal individual computational capabilities. The work also demonstrates the utility of exploratory agent-based modeling (EABM) in the engineering of artificial life-like complex adaptive systems
Computer-Related Stress and Learning Styles among Elementary School Teachers
No full textAbstract Ninety-four elementary school teachers from southern Parochial schools were surveyed using a learning style inventory to categorize learning style as visual, auditory or kinesthetic and Hudiburg's updated Computer Technology Hassles Scale. Participation in the study was voluntary and was solicited through school principals. Groups of teachers organized by learning style were formed. Multivariate comparison of these groups based upon five stress variables suggested that computer stress, particularly that related to Computer System Performance Concerns, was associated with the learning style of the teacher's who were visual learners
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No full textAbstract--Smart meter is an advanced energy meter that measures consumption of electrical energy providing additional information compared to a conventional energy meter. Integration of smart meters into electricity grid involves implementation of a variety of techniques and software, depending on the features that the situation demands. Design of a smart meter depends on the requirements of the utility company as well as the customer. This paper discusses various features and technologies that can be integrated with a smart meter. In fact, deployment of smart meters needs proper selection and implementation of a communication network satisfying the security standards of smart grid communication. This paper outlines various issues and challenges involved in design, deployment, utilization, and maintenance of the smart meter infrastructure. In addition, several applications and advantages of smart meter, in the view of future electricity market are discussed in detail. This paper explains the importance of introducing smart meters in developing countries. In addition, the status of smart metering in various countries is also illustrated. Index Terms-Communication technology, deployment, design, issues, protocols, smart meters I. INTRODUCTION mart meter is an advanced energy meter that measures the energy consumption of a consumer and provides added information to the utility company compared to a regular energy meter. Smart meters can read real-time energy consumption information including the values of voltage, phase angle and the frequency and securely communicates that data. The ability of smart meters for bidirectional communication of data enables the ability to collect information regarding the electricity fed back to the power grid from customer premises. A smart meter system includes a smart meter, communication infrastructure, and control devices. Smart meters can communicate and execute control commands remotely as well as locally. Smart meters can be used to monitor and also to control all home appliances and devices at the customer's premises. They can also collect diagnostic information about the distribution grid, home appliances, and can communicate with other meters in their reach. They can measure electricity consumption from the grid, support decentralized generation sources and energy storage devices, and bill the customer accordingly. Data collected by smart meters is a combination of parameters such as a unique meter identifier, timestamp of the data, and electricity consumption values. Smart meters can be programmed such that, only power consumed from the utility grid is billed while the power consumed from the distributed generation sources or storage devices owned by the customers are not billed. Smart meters can limit the maximum electricity consumption, and can terminate or re-connect electricity supply to any customer remotely [1], Design of future electricity markets are aimed at providing their consumers with highly reliable, flexible, readily accessible and cost-effective energy services by exploiting advantages of both large centralized generators as well as small distributed power generation devices II. COMMUNICATION TECHNOLOGIES Of all design considerations, selection of the communication network and design of the communication devices are very important and must satisfy multiple complex requirements. As discussed earlier, utilization of the smart meter system involves a huge amount of data transfer between the utility company, smart meter, and home appliances in the network. This data is sensitive, confidential and access to this data should be restricted to a few personnel. With these restrictions on data, security guidelines are formulated for transmission, collection, storage, and maintenance of the energy consumption data. The communication standards and guidelines were formulated to ensure that data transfer within the network is secure. It is equally important that this data must represent the complete information regarding the energy consumption by the customer and status of the grids without any potential manipulations or miscalculations. So, this data must be authenticated and should reflect information about the target correct devices In this figure, devices in the transmission sector ensure proper transmission of generated energy, control systems in distribution sector ensure monitoring and controlling faults, communication devices like protocol gateways, data collectors and repeaters and network operations coordinates data and control signals between all the devices in the communication network. A smart meter or an appliance that belongs to a customer can be identified by a unique identity assigned to it. In general, identities given to all components are secured by cryptographic techniques In addition to above options, Session Initiation Protocol (SIP) is a text-based signaling protocol that is used for controlling multimedia sessions such as video and Voice over Internet Protocol (VoIP) T. Mander et al. proposed a communication architecture that uses DNP3 to produce the protocol discontinuity between the DNP3 devices for regulated power system operations and TCP/IP devices for the smart load and demand management. This discontinuity in protocols limits the number of vulnerable attacks from other TCP/IP devices. Some security enhancements such as data object security and a security layer to DNP3, as this protocol by itself is not adequately safe for collaborative operations. Data object security provides several rules for accessing the data in order to avoid unauthorized access that manipulates the data and device operations GPRS technology can be a potential communication medium for transferring both the data and control signals wirelessly over long distances. In contrary to other communication network technologies, only a few communication characteristics that represent GPRS communication network have been assessed. In view of this, lack of tools for detection of a network failure would be major setback for implementing GPRS network in many geographical locations. Before deploying a GPRS based communication system in a specific location, availability an
Effects of grazing systems on herbage mass and liveweight gain of Tibetan sheep in Eastern Qinghai-Tibetan Plateau, China
No full textAbstract. Grazing strategies, consisting of grazing systems and stocking rate adjustments, have evolved from the need to sustain efficient use of the forage resources by livestock, increase animal performance and sustain forage production. A 3-year study was conducted with Tibetan sheep on the Eastern Qinghai-Tibetan Plateau, China to compare: (1) two grazing systems [season-long continuous (SLC; July to December) versus short duration with seasonal rotation (SDSR; July to September in growing-season pasture and October to December in cold-season pasture) with a stocking rate of 24 sheep months ha -1 (SM ha -1 )]; (2) SDSR system with 24, 36 and 48 SM ha -1 ; and (3) seasonal aspects of stocking rate under the SDSR system by comparing strategies of heavy stocking rate in the growing season and light stocking rate in the cold season (SDSR-HL) versus light stocking rate in the growing season and heavy stocking rate in the cold season (SDSR-LH). No differences were found between grazing systems in liveweight gain per head or per ha and in residual herbage mass. Liveweight gain per head for treatment SDSR24 was greater than for treatments SDSR36 and SDRS48, whereas liveweight gain per ha showed the opposite tendency. No differences were found between the SDSR-HL and SDSR-LH treatments in liveweight gain per head or per ha, whereas the ratio of residual herbage mass at the end of grazing the growing-season pasture to the cold pasture of treatment SDSR-LH was more than twice that of treatment SDSR-HL. Daily liveweight gain of Tibetan sheep decreased linearly with increasing grazing pressure in both growing and cold seasons. It was estimated that, at a grazing pressure index of 310 sheep days t -1 DM peak herbage mass, liveweight gain per head and ha appears to be optimised over the whole grazing period. Liveweight loss by Tibetan sheep during the cold season was apparent regardless of grazing pressure indicating that temperature had a stronger influence on sheep performance in the cold season than herbage availability
Self-referent phenotype matching and long-term maintenance of kin recognition
No full textAvailable online xxx MS. number: A10-00257 Keywords: ground squirrel hibernation kin recognition nepotism olfactory discrimination self-referential phenotype matching Self-referential phenotype matching, or using one's own cues as a referent for recognizing kin, is expected in species with multiple paternity or maternity to discriminate among full siblings and halfsiblings, or in nepotistic contexts to accurately assess relatedness. It would also facilitate optimal inbreeding and outbreeding. Self-matching has been predicted for Belding's ground squirrels, Urocitellus beldingi, yet previous work could not rule out the possibility that animals use family cues rather than or in addition to their own cues for recognition. After hibernation, U. beldingi recognize their littermates but not previously familiar nonkin. Kin templates, including cues of mother and littermates, may be maintained throughout life, or, they may be lost during hibernation with memories of unrelated individuals, in which case self-matching must be used to create a new template in the spring. Using a cross-fostering design, these two possibilities were tested with olfactory discrimination tests after ground squirrels aroused from hibernation. Yearlings recognized their siblings, but not fostermates they had been reared with since birth, demonstrating that kin templates are lost over winter and self-matching is used to recognize kin after hibernation. Results are discussed in terms of plasticity of kin recognition systems, the costs and benefits of maintaining social memories, and the contexts in which templates are updated.
