The ever-increasing technological advances in embedded systems engineering, together with the proliferation of small-size sensor design and deployment, have enabled mobile devices (e.g., smartphones) to recognize daily occurring human based actions, activities and interactions. Therefore, inferring a vast variety of mobile device user based activities from a very diverse context obtained by a series of sensory observations has drawn much interest in the research area of ubiquitous sensing. The existence and awareness of the context provides the capability of being conscious of physical environments or situations around mobile device users, and this allows network services to respond proactively and intelligently based on such awareness. Hence, with the evolution of smartphones, software developers are empowered to create context aware applications for recognizing human-centric or community based innovative social and cognitive activities in any situation and from anywhere. This leads to the exciting vision of forming a society of ``Internet of Things" which facilitates applications to encourage users to collect, analyze and share local sensory knowledge in the purpose for a large scale community use by creating a smart network which is capable of making autonomous logical decisions to actuate environmental objects. More significantly, it is believed that introducing the intelligence and situational awareness into recognition process of human-centric event patterns could give a better understanding of human behaviors, and it also could give a chance for proactively assisting individuals in order to enhance the quality of lives. Mobile devices supporting emerging computationally pervasive applications will constitute a significant part of future mobile technologies by providing highly proactive services requiring continuous monitoring of user related contexts. However, the middleware services provided in mobile devices have limited resources in terms of power, memory and bandwidth as compared to the capabilities of PCs and servers. Above all, power concerns are major restrictions standing up to implementation of context-aware applications. These requirements unfortunately shorten device battery lifetimes due to high energy consumption caused by both sensor and processor operations. Specifically, continuously capturing user context through sensors imposes heavy workloads in hardware and computations, and hence drains the battery power rapidly. Therefore, mobile device batteries do not last a long time while operating sensor(s) constantly. In addition to that, the growing deployment of sensor technologies in mobile devices and innumerable software applications utilizing sensors have led to the creation of a layered system architecture (i.e., context aware middleware) so that the desired architecture can not only offer a wide range of user-specific services, but also respond effectively towards diversity in sensor utilization, large sensory data acquisitions, ever-increasing application requirements, pervasive context processing software libraries, mobile device based constraints and so on. Due to the ubiquity of these computing devices in a dynamic environment where the sensor network topologies actively change, it yields applications to behave opportunistically and adaptively without a priori assumptions in response to the availability of diverse resources in the physical world as well as in response to scalability, modularity, extensibility and interoperability among heterogeneous physical hardware. In this sense, this dissertation aims at proposing novel solutions to enhance the existing tradeoffs in mobile sensing between accuracy and power consumption while context is being inferred under the intrinsic constraints of mobile devices and around the emerging concepts in context-aware middleware framework.

In this thesis I provide general guidelines for a commercial building owner’s decision making process for heating, ventilation, and air-conditioning (HVAC) system energy efficiency projects, discuss an example HVAC project at an existing building, and recommend the most energy-efficient, cost-effective project option. First, a building’s HVAC system’s inefficiencies are identified. The systems and the components can be investigated to understand the nature of the operations. In the building owner’s interests, possible alternatives can be developed to address the systems with improvements. Consulting engineers, contractors, and other building professionals can assist in this process. There are necessary engineering and construction considerations for defining realistic project alternatives. With the alternatives, there are costs, benefits, and trade-offs. The costs, which mainly include the investment and the operational costs, and the benefits, which mainly include the available financial incentives, defined in dollars, are identified for the alternatives. The alternatives can be evaluated with Building Life Cycle Cost (BLCC) software. In this evaluation the net present-value (NPV) method is used to rank the alternatives. Then, the highest-ranking, lowest life-cycle cost, alternative is recommended for the owner. In the example, an existing commercial building’s HVAC systems are considered. The construction plans, the facilities records, and the existing field conditions were investigated and analyzed. A few operational inefficiencies were identified. To address two of these existing inefficiencies, there were alternatives considered to replace the standard-efficiency air handling unit motors with premium-efficiency motors and to renovate the ventilation system with an energy recovery wheel. The investment costs, the available rebates, the net annual energy savings, and the energy and other operational costs were estimated, over a 30-year study period, for each of these alternatives, and compared to the costs of the existing system. The BLCC evaluations were performed across a range of discount rates in the present-value calculations. Based on the lowest present-value life-cycle cost reports, the premium-efficiency motor replacement project only is recommended. / text

Wireless Sensor Networks (WSNs) continue to evolve as new applications emerge. In the recent past, WSNs were mostly single sink networks with a few number of homogeneous and static sensor nodes. Now, several applications require networks with multiple and moving sinks and targets as well as thousands of heterogeneous devices. However, the same constraints remain: sensor nodes continue to be very limited in resources, posing new challenges in the design of scalable and energy-efficient algorithms and communication protocols to support these new applications. This dissertation first addresses the problem of sink localization in large scale WSNs. A scalable and energy-efficient sink localization mechanism, called the Anchor Location Service (ALS), is introduced to support the use of location-based routing protocols. ALS avoids frequent and costly flooding procedures derived from the mobility of the sinks and targets, and utilizes face routing to guarantee the success of localization. The problem of topology control in heterogeneous environments is addressed next. A new topology control mechanism, the Residual Energy-Aware Dynamic (READ) algorithm, is devised to extend the lifetime of the network while maintaining connectivity. READ extends the lifetime of the network by assigning a more prominent role to more powerful devices. ALS and READ are evaluated and compared with other well-known protocols using analytical means and simulations. Results show that ALS provides a scalable sink location service and reduces the communication overhead in scenarios with multiple and moving sinks and targets. Results also show that READ increases both the network lifetime and the packet delivery rate.

Increasing power dissipation is one of the most serious challenges facing designers in the microprocessor industry. Power dissipation, increasing wire delays, and increasing design complexity have forced industry to embrace multi-core architectures or chip multiprocessors (CMPs). While CMPs mitigate wire delays and design complexity, they do not directly address single-threaded performance. Additionally, programs must be parallelized, either manually or automatically, to fully exploit the performance of CMPs. Researchers have recently proposed an architecture called Explicit Data Graph Execution (EDGE) as an alternative to conventional CMPs. EDGE architectures are designed to be technology-scalable and to provide good single-threaded performance as well as exploit other types of parallelism including data-level and thread-level parallelism. In this dissertation, we examine the energy efficiency of a specific EDGE architecture called TRIPS Instruction Set Architecture (ISA) and two microarchitectures called TRIPS and TFlex that implement the TRIPS ISA. TRIPS microarchitecture is a first-generation design that proves the feasibility of the TRIPS ISA and distributed tiled microarchitectures. The second-generation TFlex microarchitecture addresses key inefficiencies of the TRIPS microarchitecture by matching the resource needs of applications to a composable hardware substrate. First, we perform a thorough power analysis of the TRIPS microarchitecture. We describe how we develop architectural power models for TRIPS. We then improve power-modeling accuracy using hardware power measurements on the TRIPS prototype combined with detailed Register Transfer Level (RTL) power models from the TRIPS design. Using these refined architectural power models and normalized power modeling methodologies, we perform a detailed performance and power comparison of the TRIPS microarchitecture with two different processors: 1) a low-end processor designed for power efficiency (ARM/XScale) and 2) a high-end superscalar processor designed for high performance (a variant of Power4). This detailed power analysis provides key insights into the advantages and disadvantages of the TRIPS ISA and microarchitecture compared to processors on either end of the performance-power spectrum. Our results indicate that the TRIPS microarchitecture achieves 11.7 times better energy efficiency compared to ARM, and approximately 12% better energy efficiency than Power4, in terms of the Energy-Delay-Squared (ED²) metric. Second, we evaluate the energy efficiency of the TFlex microarchitecture in comparison to TRIPS, ARM, and Power4. TFlex belongs to a class of microarchitectures called Composable Lightweight Processors (CLPs). CLPs are distributed microarchitectures designed with simple cores and are highly configurable at runtime to adapt to resource needs of applications. We develop power models for the TFlex microarchitecture based on the validated TRIPS power models. Our quantitative results indicate that by better matching execution resources to the needs of applications, the composable TFlex system can operate in both regimes of low power (similar to ARM) and high performance (similar to Power4). We also show that the composability feature of TFlex achieves a signification improvement (2 times) in the ED² metric compared to TRIPS. Third, using TFlex as our experimental platform, we examine the efficacy of processor composability as a potential performance-power trade-off mechanism. Most modern processors support a form of dynamic voltage and frequency scaling (DVFS) as a performance-power trade-off mechanism. Since the rate of voltage scaling has slowed significantly in recent process technologies, processor designers are in dire need of alternatives to DVFS. In this dissertation, we explore processor composability as an architectural alternative to DVFS. Through experimental results we show that processor composability achieves almost as good performance-power trade-offs as pure frequency scaling (no changes in supply voltages), and a much better performance-power trade-off compared to voltage and frequency scaling (both supply voltage and frequency change). Next, we explore the effects of additional performance-improving techniques for the TFlex system on its energy efficiency. Researchers have proposed a variety of techniques for improving the performance of the TFlex system. These include: (1) block mapping techniques to trade off intra-block concurrency with communication across the operand network; (2) predicate prediction and (3) operand multi-cast/broadcast mechanism. We examine each of these mechanisms in terms of its effect on the energy efficiency of TFlex, and our experimental results demonstrate the effects of operand communication, and speculation on the energy efficiency of TFlex. Finally, this dissertation evaluates a set of fine-grained power management (FGPM) policies for TFlex: instruction criticality and controlled speculation. These policies rely on a temporally and spatially fine-grained dynamic voltage and frequency scaling (DVFS) mechanism for improving power efficiency. The instruction criticality policy seeks to improve power efficiency by mapping critical computation in a program to higher performance-power levels, and by mapping non-critical computation to lower performance-power levels. Controlled speculation policy, on the other hand, maps blocks that are highly likely to be on correct execution path in a program to higher performance levels, and the other blocks to lower performance levels. Our experimental results indicate that idealized instruction criticality and controlled speculation policies improve the operating range and flexibility of the TFlex system. However, when the actual overheads of fine-grained DVFS, especially energy conversion losses of voltage regulator modules (VRMs), are considered the power efficiency advantages of these idealized policies quickly diminish. Our results also indicate that the current conversion efficiencies of on-chip VRMs need to improve to as high as 95% for the realistic policies to be feasible. / text

Οι τελευταίες εξελίξεις στα πεδία της ασύρματης μετάδοσης ενέργειας και των υλικών μπαταρίας προσφέρουν καινούριες δυνατότητες για τη διαχείριση της διαθέσιμης ενέργειας στα Ασύρματα Δίκτυα Αισθητήρων. Στο πρώτο πεδίο, έχει αποδειχθεί ότι, μέσω ισχυρά συζευγμένων μαγνητικών συντονισμών, η αποδοτικότητα μεταφοράς 60 watts ισχύος σε απόσταση δύο μέτρων φτάνει το 40% και σε απόσταση ενός μέτρου φτάνει το 75%. Επίσης, εμπορικά προϊόντα που κάνουν χρήση αυτής της τεχνολογίας, ήδη κυκλοφορούν στην αγορά. Στο δεύτερο πεδίο, πραγματοποιήθηκε πρόσφατα άκρως ταχεία φόρτιση με μπαταρίες LiFePO4, επιτρέποντας πλήρη φόρτιση σε μερικά μόνο δευτερόλεπτα. Αυτές οι τεχνολογικές εξελίξεις ανοίγουν το δρόμο προς ένα νέο παράδειγμα για τα Ασύρματα Δίκτυα Αισθητήρων, τα Ασύρματα Επαναφορτιζόμενα Δίκτυα Αισθητήρων, τα οποία αποτελούνται από κόμβους αίσθησης (στάσιμους ή κινητούς) και έναν ή περισσότερους κινητούς κόμβους με υψηλό απόθεμα ενέργειας. Οι τελευταίοι, χρησιμοποιώντας τις προαναφερθείσες τεχνολογίες, επιτυγχάνουν γρήγορη ασύρματη φόρτιση των κόμβων αίσθησης. Με αυτόν τον τρόπο, μας δίνεται η δυνατότητα διαχείρισης του πολύ περιορισμένου πόρου της ενέργειας στο δίκτυο, με περισσότερη λεπτομέρεια και αποδοτικότητα. Σημαντικό είναι το γεγονός ότι, από την προοπτική των κόμβων αίσθησης, η διαχείριση της ενέργειας μπορεί να πραγματοποιηθεί παθητικά και χωρίς την υπολογιστική και επικοινωνιακή επιβάρυνση που εισάγουν σύνθετοι αλγόριθμοι διαχείρισης ενέργειας. Επίσης, η διαδικασία φόρτισης μπορεί να πραγματοποιηθεί με πρωτόκολλα τα οποία μελετώνται και σχεδιάζονται ανεξάρτητα από το υποκείμενο πρωτόκολλο δρομολόγησης που χρησιμοποιείται για την μετάδοση των δεδομένων. Το πρόβλημα. Έστω ένα Ασύρματα Επαναφορτιζόμενο Δίκτυο Αισθητήρων στο οποίο οι κόμβοι αίσθησης μεταδίδουν δεδομένα σε ένα κέντρο ελέγχου χρησιμοποιώντας ένα πρωτόκολλο δρομολόγησης και ο κινητός κόμβος φόρτισης, με απόθεμα ενέργειας σημαντικά μεγαλύτερο από έναν κόμβο αίσθησης, είναι ικανός να αναπληρώνει ασύρματα την ενέργεια των κόμβων αίσθησης. Το πρόβλημα που εξετάζουμε είναι η εύρεση της καλύτερης διαμόρφωσης του κινητού κόμβου φόρτισης, με σκοπό τη βελτίωση της ενεργειακής αποδοτικότητας του δικτύου και της παράτασης της διάρκειας ζωής των κόμβων. Η συνεισφορά μας. Αν και έχουν γίνει ήδη σημαντικές ερευνητικές προσπάθειες για την ενεργειακά αποδοτική δρομολόγηση του κινητού κόμβου αίσθησης, οι περισσότερες προτεινόμενες λύσεις στη βιβλιογραφία μέχρι στιγμής υποθέτουν ολική γνώση επάνω στο δίκτυο. Αντιθέτως, οι λύσεις που παρέχουμε είναι πλήρως κατανεμημένες και προσαρμοστικές, και βασίζονται σε τοπική δικτυακή πληροφορία. Επίσης, τα πρωτόκολλά μας για τον κινητό κόμβο αίσθησης μπορούν να χρησιμοποιηθούν σε συνδυασμό με κάθε πρωτόκολλο δρομολόγησης και προσαρμόζονται στην κατανομή των κόμβων αίσθησης στο επίπεδο. Τέλος αναγνωρίζουμε και σχεδιάζουμε σημαντικές παραμέτρους της διαδικασίας φόρτισης, όπως i) το ποσό της συνολικής αρχικής ενέργειας του δικτύου που δεσμεύει ο κινητός κόμβος φόρτισης, ii) το επίπεδο στο οποίο πρέπει να αναπληρώνεται η ενέργεια του κάθε κόμβου αίσθησης, iii) ποιες τροχιές πρέπει να ακολουθεί ο κινητός κόμβος φόρτισης ώστε να φορτίσει τους κόμβους αίσθησης. / Recent advances in the fields of wireless energy transmission and batteries material offer new possibilities for managing the available energy in WSNs. In the first field, the technology of highly efficient wireless energy transmission was proposed for efficient, non-radiative energy transmission over mid-range. It has been shown that through strongly coupled magnetic resonances, the efficiency of transferring 60 watts of power over a distance in excess of 2 meters is as high as 40%. Industry research also demonstrated that it is possible to improve transferring 60 watts of power over a distance of up to one meter with efficiency of 75%. At present, commercial products utilizing wireless energy transmission have been available on the market. In the second field, ultra-fast charging was recently realized in LiFePO4 by creating a fast ion-conducting surface phase through controlled off-stoichiometry. These technologies lead the way towards a new paradigm for wireless sensor networks; the Wireless Rechargeable Sensor Networks (WRSNs), which consist of sensor nodes that may be either stationary or mobile, as well as few mobile nodes with high energy supplies. The latter, by using wireless energy transmission technologies are capable of fast charging sensor nodes. This way, the highly constrained resource of energy can be managed in great detail and more efficiently. Another important aspect is the fact that energy management in WRSNs can be performed passively from the perspective of sensor nodes and without the computational and communicational overhead introduced by complex energy management algorithms. Finally, WRSNs allow energy management to be studied and designed independently of the underlying routing protocol used for data propagation. The Problem. Let a Wireless Rechargeable Sensor Network consisting of a set of stationary sensor nodes and a special mobile node called Mobile Charger. The sensor nodes are deployed uniformly at random over a network area and propagate data to a Sink using a routing protocol. The Mobile Charger has finite energy supplies, that are significantly greater than those of a single sensor node, and is capable of charging the sensors. The problem we study is identifying best possible configuration of the Mobile Charger in order to improve energy efficiency and to prolong the lifetime of the network. Our Contribution. While considerable research efforts have been invested into energy efficient scheduling of the Mobile Charger, proposed solutions in the literature so far require a global knowledge of the state of the network. On the contrary, the solutions proposed in this work are fully distributed and adaptive, and rely solely on local information. Furthermore, our proposed algorithm for the Mobile Charger can be used in combination with any underlying routing protocol and adapts on the distribution of sensors in the network area. We identify and investigate the following trade-offs: i) how the total available energy of the network should be split between sensor nodes and the Mobile Charger ii) given that the energy the charger may deliver to the nodes is finite, whether each sensor will be fully or partially charged and iii) what is the trajectory the Mobile Charger should follow in order to charge the sensor nodes.

Roughly 130 000 dwellings have been officially registered since Norway as of summer 2009 passed their bill “Energimerkeforskriften” on energy performance certificates in buildings. The main objective is to decrease the total amount of national energy consumption by producing a methodology of calculation of the integrated energy performance of buildings as well as proposing cost effective measures to lower each building’s energy consumption.  As the measures should not contravene nor be incompatible with the intended quality and character of the building, the “Energimerkeforskriften” exempts buildings that due to their historical and cultural values are protected cultural heritage legislation. The current system offers a couple of professional certification alternatives, but when two online semi-automatic methods developed specifically for non-professionals are by far the most used, and since the methods of calculation primarily have focused on modern building materials and construction, the rest of the historical building stock stands literally unprotected by incorrect performance certificates and high-risk energy efficient measures.  The objective of this thesis is to identify if the current Norwegian energy certificate system poses a threat to older buildings. It also tries to pinpoint relevant additions in order to minimize those potential risks in a near future by relating potential impact to what is determined as the main character-defining values of a building. The results show that the system clearly has its flaws, mainly regarding the estimation of energy consumption, and that the automatically recommended energy efficient measures would pose a serious potential threat to the historical building stock of Norway if they were to be implemented. / Bakgrunden till arbetet är de krav som EU direktivet (2002/91/EF) om byggnaders energiprestanda ställer på upprättande av energideklarationer och energieffektiviserande åtgärdsförslag. Till följd av att direktivet lämnat utrymme för given tillämpningsmetod har Norge utvecklat ett deklarationssystem där gemene hus- och fastighetsägare fått möjlighet att själva genomföra sin energideklaration, något som i andra länder enbart får genomföras av oberoende experter eller företag. Sedan systemet togs i bruk under slutet av 2009 har cirka 130 000 unika energideklarationer genomförts av privatpersoner genom den officiella hemsidan för Energimerke-systemet. Hemsidan tillhandahåller ett energiberäkningsprogram vilket med hjälp av olika tekniska och byggnadsrelaterade uppgifter som registreras av använder genererar en energideklaration. Systemets beräkning av byggnadens energibehov och uppvärmningssystemets verkningsgrad faller sedan samman i ett energimerke som i sin tur är ett krav att ha vid försäljning eller uthyrning av en bostad. Utöver själva beviset rekommenderas även ett antal energieffektiviserande åtgärder.  Med ett rådande undantag för kulturhistoriskt skyddade byggnader och ett system som inte är anpassat efter äldre konstruktioner verkar det dock kunna finnas vissa risker med den nuvarande metoden. För att genomföra en första granskning av systemet och dess möjliga konsekvenser för äldre byggnader i Norge har detta arbete därför ställt ett stort statistiskt underlag av tidigare energideklarationer mot utfallet i några fallstudier och simuleringar. Syftet är att ge svar på huruvida energideklarationssystemet utgör ett hot mot äldre byggnaders karaktärsbärande värden eller ej, samt försöka identifiera hur systemet kan förbättras och utvecklas. Ett viktigt moment i att försöka svara på arbetets frågeställningar har utgjorts av ett resonemang vilket lett fram till det sammanvägande begreppet karaktärsbärande värden. Satt i förhållande till energideklarationssystemets åtgärdsförslag och lagrummets egna varsamhetsparagrafer har det kunnat ge en fingervisning om vilka åtgärder som utgör störst risk för äldre byggnader.  Resultaten visar att systemet med estimerade energiberäkningar verkar genera felaktiga värden som förvärras ju äldre och enklare byggnaderna respektive registreringarna är. Det är även tydligt att åtgärder med hög risk för byggnaders karaktärsbärande värden ständigt återkommer som förslag samtidigt som systemet ej heller tar hänsyn till kostnadseffektiva aspekter. För att minimera riskerna föreslås att systemets tekniska ramar utvidgas samtidigt som systemets åtgärdsförslag ses över och eventuellt begränsas till att gälla brukarrelaterade råd. / Spara och Bevara

Many rural communities in South Africa do not have running water or electricity. The fetching and heating of water is therefore a time consuming and expensive daily ritual. The use of energy sources such as wood or coal are not readily available and cause environmental pollution. Although solar water heaters are commonly available in South Africa, they are very seldom used in rural areas. Whilst this can mostly be attributed to a high system cost, current designs also do not cater for specific rural problems such as the transporting or purification of water. A prototype model, designed with such an approach in mind, has already been constructed by TEMM International (Pty.) Ltd. The Solar Heat Barrow (SHB) was developed in the 1992 to 2003 period with the intention of combining a number of functions at low cost. Specific requirements were: low cost, a suitable design and materials for manufacture in large volume, sufficiently durable taking into account the harsh conditions of use. suitability for cases where no in-house piped water supply was available, the use of appropriate technology and the improvement of quality of life. The unit combines the absorption of solar radiation, the heating of a relatively small volume of water, the transport of the water from the point of supply and the storage of the hot water until it is used. Untreated water sources such as surface waters (streams, rivers, lakes, etc.) or unprotected open wells are the vehicles for waterborne bacterial diseases such as cholera and typhoid fevers. In the case where water is collected from these sources, the SHB has a build-in Purification Dispenser that purifies the water in the collector against waterborne bacterial diseases. Certain research questions need to be answered. They will be answered by demonstrating the SHB in two communities where no in-house piped water supply is available and by establishing the socio-economic response of the users. The research questions are as follow: What are the responses of the users concerning the SHB, in comparison to those of a control group, regarding its operation, durability, utility and satisfaction of needs? What is the daily use of hot water and the reduction in energy use and cost? To what extent will the target community purchase the SHB at the full or subsidised commercial price? Is there a business case that can be developed for the large scale production, marketing. financing and Small, Medium and Micro Enterprises (SMME) development of the SHB? It was decided to choose a community in the Valley of Thousand Hills in KwaZulu Natal as the demonstration site. The name of the community is Mabedlane. It is a remote rural area 20 km's north of Botha's Hill and is situated along the Umgeni River. The community is dependent on the river for domestic water. Most families are headed by women. The area has low levels of infrastructure, poor roads, a high unemployment rate and poor health facilities. The first survey, which was conducted before the test period started, showed a very positive response from potential users. From 112 questionnaires that were given to the people of Mabedlane, all indicated that they were interested in a product that can transport and heat water for domestic use. The socio-economic study has shown that the price per unit needs to be adapted as 85% of the people who participated in the survey indicated that they would only pay less than R100 for the product. 15% indicated that they would pay between RlOO and R200. From the second and third questionnaires it was clear that the users were satisfied with the heating performances of the SHB. The community was very interested in purchasing a SHB. They have realised that a SHB will improve their standard of living and regard it as a necessity in their day to day activities. It is apparent that people, who will benefit from a SHB most, are those who will not be able to pay the full retail price. Therefore, new business strategies have to be researched when implementing the SHB to the target market in South Africa. The idea of considering ways to sponsorlfund the SHB must also be investigated. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2004.

Buildings are the primary user of energy in the USA. Within homes, the heating, ventilation, and air condition (HVAC) system is the largest energy consumer. This study: (i) developed a new methodology for simulating filter loading in-situ; (ii) observed the impact of filter loading on AC performance in-situ; and (iii) provided a greater understanding of when a filter is “dirty” and should be replaced. Six central AC systems in the Atlanta metro-region were evaluated. Filter loading was simulated by installing the TrueFlow® airflow metering device and partially taping off the face at 3 different increments. This resulted in measurements at 5 discrete static pressures (no filter, TrueFlow, TrueFlow Taped one, TrueFlow Taped two, and TrueFlow Taped three). The pilot study found that as filter pressure drop increased, airflow rates generally decreased, resulting in higher differences in temperature across the evaporator coil (∆T). There was no observed correlation between absolute humidity across the evaporator coil and either filter pressure drop or system airflow. Overall, as airflow decreased so did sensible, latent, and total capacity. This research can inform decisions about filter replacement and be used to evaluate computer simulation models of HVAC performance.

In this thesis, a resource allocation problem in OFDMA is studied for the energy efficiency of wireless network. The objective is to minimize the total energy consumption which includes transmission energy consumption, and circuit energy consumption at both transmitter and receiver with required per user’s rate constraint. For problem solution, a heuristic algorithm with low computational complexity and suboptimal solution is proposed, developed in two steps with an increasing order of complexity. Besides, a bounding scheme based on model linearization of formulated nonlinear system model is also proposed to give lower and upper bounds for both small- and large-scale OFDMA network for further algorithm performance evaluation, while the implemented exhaustive search is only capable to provide the optimal solution for small-scale instance for algorithm performance evaluation. Numerical results show that the proposal heuristic algorithm can achieve near-optimal performance with applicable computational complexity even for large-scale networks, and that the bounds from the bounding scheme are very tight for both small- and large-scale OFDMA networks.

Tyrimo tikslas – ištirti medienos džiovyklos, kūrenamos biokuru, energijos sąnaudas ir energinį efektyvumą. Tyrimo uždaviniai – išanalizuoti biokuro katilinės technologinį procesą, nustatyti biokuro charakteristikas ir biokuro poreikius medienos džiovinimui, sudaryti džiovinamos medienos elektros ir šiluminės energijos sąnaudų skaičiavimo metodiką. Eksperimentinio tyrimo metu nustatytas biokuro (pjuvenų) šilumingumas (9,3 MJ/kg) ir jo drėgnis (47,0 %). Nustatytos katilinės elektros įrenginių ir medienos džiovyklos suminės energijos sąnaudos, kurios siekia 686 MJ/m3 išdžiūvusios medienos. / The aim – to investigate wood drying, burning biofuels, energy consumption and energy efficiency. Objectives of the study – to analyse the biofuel boiler process that determine the characteristics of biofuels and biofuel needs of timber drying, consist of dried wood of electrical and thermal energy cost calculation methodology. Results of experimental investigation shows that calorific value of biofuel (saw dust) is 9,3 MJ/kg and humidity – 47,0 %. The total energy consumption of electrical installations and wood drying machine has been determined, which shows the total energy input of 686 MJ/m3 dried wood.