Santrauka Darbo apimtis 52 puslapiai, įskaitant 39 paveikslėlius ir 4 lenteles. Informacijos šaltinių sąraše 35 šaltiniai. Darbo pradžia 2007 09 01, pabaiga 2009 05 28. Tyrimų objektas. Trijų tipų karvidžių mikroklimatas: apšiltintu stogu 400 vietų boksinė karvidė; šalta 240 vietų boksinė karvidė, bei 130 vietų su perdengimu pusiau gili karvidė. Tyrimų tikslas – įvertinti įvairiai apšiltintų karvidžių mikroklimatą šiltuoju ir šaltuoju metų laikotarpiu, bei nustatyti šilumos nuostolius tvartuose. Išnagrinėjus literatūroje paskelbtus tyrimų duomenis galima daryti išvadą, norint, kad gyvulių produktyvumas būtų didžiausias, o pašarų sąnaudos – mažiausios, karvidėje optimali rekomenduotina temperatūra turi būti nuo -7 iki +24 oC. Tačiau mokslininkų nustatyta, kad jei gyvulius gerai šersime ir jie bus produktyvūs, tai minus 15 oC ir dar žemesnė temperatūra nėra pavojinga. Šiltuoju metų laikotarpiu tyrimais nustatyta, kad karvidžių mikroklimato parametrai buvo optimalūs ir neviršijo rekomenduojamų normų, o šaltuoju metų laikotarpiu santykinis oro drėgnis 15,3 % viršijo optimalius mikroklimato reikalavimus, o ypač didelis buvo iki 95 % apšiltintoje pusiau gilioje karvidėje. To priežastis, kad norint palaikyti tvarte aukštesnę temperatūrą buvo per daug pridaryti vėdinimo kanalai. Apskaičiavus šilumos nuostolius karvidėse nustatėme, kad didžiausi šilumos nuostoliai būna su pašalinamu iš patalpos oru (81 % nuo bendrų nuostolių). / Summary Scope of work pageis 52, including 39 pictures and 4 tables. The information sources listed 35 sources. Beginning in 2007 09 01, the end of 2009 05 28. Work item. Three types of cowsheds microclimate: warm roof of 400 seats box cowshed; cold of 240 seats box cowshed, and 130 seats with a semi-deep reroof cowshed. The aim - evaluate the warm various cowsheds microclimate warm and cold seasons, and to determine the heat losses from stables. The examination of the literature published research data it can be concluded for that animal productivity is highest, while feed costs - the minimum, recommended cowshed optimum temperature must be between -7 to +24 oC. However, researchers found that if the stock is well feeder, and they will be productive, it is minus 15 ° C and lower temperatures are not dangerous. In warm season during the research found that cowsheds microclimatic parameters were optimized and did not exceed the recommended rate, and cold season period, the relative humidity is 15,3% above the optimum microclimatic requirement, in particularly was high up to 95% in the warm semi-deep cowshed. The reason that, in order to maintain a higher temperature in the stables during impose a lot of ventilation ducts. Calculated heat loss cowsheds found that the maximum heat loss is to be with removable from the room air (81 % of the total losses).

Darbe pateikti kombainų su tangentiniu kūlimo aparatu ir dviem ašiniais – rotoriniais šiaudų separatoriais kukurūzų burbuolių nuėmimo grūdų nuostolių ir sužalojimo tyrimų rezultatai. Gamybinėmis sąlygomis, nuimant kukurūzų burbuoles, įvertintas kombaino su tangentiniu kūlimo aparatu ir dviem ašiniais rotoriniais separatoriais darbas ir pagrįsti kūlimo aparato racionalūs technologiniais parametrais. Literatūros apžvalgoje įvertinta kukurūzų burbuolių nuėmimo technologijos, kitų tyrėjų nustatyti burbuolių kūlimo technologiniai parametrai. Lietuvoje gamybinėmis sąlygomis nėra tirtas kukurūzų burbuolių nuėmimas, nenustatyta kūlimo aparato racionalūs technologiniai parametrai ir jų įtaka grūdų sužalojimui. Nustatyta, kad kuliant vidutinio drėgnumo kukurūzų burbuoles, leistinoji grūdų sužalojimo riba 3% nebuvo viršyta, kai kūlimo būgno spragilai judėjo 11,3 m s-1. Kombaine su dviem ašiniais rotoriniais separatoriais galima sumažinti kūlimo būgno spragilų judėjimo greitį, nes nevisiškai iškultas burbuoles iškulia ašinių rotorinių separatorių dantys. Grūdų sužalojimui sumažinti reikia suderinti kūlimo būgno spragilų judėjimo greitį ir tarpą tarp būgno spragilų ir pobūgnio skersinių juostų. Kombainuose Claas Lexion racionalus tarpas tarp kūlimo būgno spragilų ir pagrindinio pobūgnio trečiosios skersinės juostos priklauso nuo kuliamų burbuolių vidutinio skersmens ir gali būti keičiamas nuo 27 iki 34 mm. Kombainas Claas Lexion 600 per technologinę valandą prikūlė 52,33±4,56 t grūdų... [toliau žr. visą tekstą] / This work presents the results of maize harvesting, using combine harvester with two axial rotary separators, research for 2011-2012. Literature study has shown that there are not many researches made on maize harvesting in Lithuania. Studies have found that the average moisture content of threshing corn cobs, grain permissible limit of 3% of the damage has not been exceeded, the threshing cylinder peripheral speed 11.3 m s -1. It was found that minimum grain scattered on soil and grains damaged were when feed rate were 19.9 kg s-1. Average grain losses were > 300 kg ha-1. The upper scaled sieve of combine harvester should be replaced with long scaled sieve. Rational speed of tangential threshing apparatus rasp bars is 12 m s-1, and the gap between threshing cylinder and concave can be adjusted 30 to 36 mm. The gap between the threshing drum rasp bars and concave crossbars has an impact on grain damage.

With increasing amount of user data and applications in wireless communication technology, demands are growing on performance and fabrication costs. One way to decrease cost is to integrate the building blocks in an RF system where digital blocks and high power amplifiers then are combined on one chip. This thesis presents LDMOS transistors integrated in a 65 nm CMOS process without adding extra process steps or masks. High power performance of the LDMOS is demonstrated for an integrated WLAN-PA design at 2.45 GHz with 32.8 dBm output power and measurements also showed that high output power is achievable at 5.8 GHz. For the first time, this kind of device is moreover demonstrated at X-band with over 300 mW/mm output power, targeting communication and radar systems at 8 GHz. As SOI is increasing in popularity due to better device performance and RF benefits, the buried oxide can cause thermal problems, especially for high power devices. To deal with self-heating effects and decrease the RF substrate losses further, this thesis presents a hybrid substrate consisting of silicon on top of polycrystalline silicon carbide (Si-on-poly-SiC). This hybrid substrate utilizes the high thermal conductivity of poly-SiC to reduce device self-heating and the semi-insulating properties to reduce RF losses. Hybrid substrates were successfully fabricated for the first time in 150 mm wafer size by wafer bonding and evaluation was performed in terms of both electrical and thermal measurements and compared to a SOI reference. Successful LDMOS transistors were fabricated for the first time on this type of hybrid substrate where no degradation in electrical performance was seen comparing the LDMOS to identical transistors on the SOI reference. Measurements on calibrated resistors showed that the thermal conductivity was 2.5 times better for the hybrid substrate compared to the SOI substrate. Moreover, RF performance of the hybrid substrate was investigated and the semi-insulating property of poly-SiC showed to be beneficial in achieving a high equivalent substrate parallel resistance and thereby low substrate losses. In a transistor this would be equal to better efficiency and output power. In terms of integration, the hybrid substrate also opens up the possibility of heterogeneous integration where silicon devices and GaN devices can be fabricated on the same chip.

The research problem of this mini-dissertation involves the conflicts between human and wildlife populations and the trialing of ‘compensation’ payouts that are emerging as a critical test within the conservancy. Crop raiders such as elephants, buffaloes, hippopotamus, bush pigs and small rodents, diminish farmers’ resource bases and cash crops, while carnivores are responsible for livestock losses. The aim of the research is to assess the level of community understanding of the compensation scheme and the impact of human wildlife interaction within the conservancy. This mini-dissertation investigated the level of community understanding about the Human Animal Conservancy Self-Insurance Scheme (HACSIS), and the impact of human-wildlife conflicts within the Kwandu Conservancy. Some of the research data were obtained from the conservancy game guards’ event book system, and the actual field research data were collected from the 1st August to 20th August 2006. The researcher conducted a total of 35 interviews, whereby 32 involved face-to-face interviews with single individuals, and 3 separate focus group discussions that consisted of four, five and two conservancy members. The interviews averaged 30 minutes in length. Each interview was preceded by a careful explanation of the purposes of the work, stressing that the intent was to evaluate their understanding and perceptions on HACSIS, the impact of human-wildlife conflicts and to explore better management strategies. The researcher has taken into account that the communities might exaggerate the wildlife problem based on his previous experience with the adjacent conservancy, in the hopes of gaining more compensation – they also use the researcher as a way to vent their frustration at the problem. On the assumption that there may be an element of exaggeration verification of these was obtained from the Event Book System (a manual book used by the Community Game Guards for recording both crops and livestock incidents on daily basis). This mini-dissertation reveals that 74.3 % (n = 26) of respondents are aware of the existence of the HACSIS program and its role, while 17.1 % of respondents had no idea about the scheme’s presence and its involvement to minimize the impact felt by communities when they lose livestock to predators. The percentage of respondents who claimed that they had heard of the scheme’s existence but had no knowledge of its role was 8.6 %. In addition, most respondents (n = 15) claimed that the conservancy committee did not explain to them why their claim forms were rejected. In contrast, some respondents (n = 6) did received feedback on rejected claim forms. HACSIS was not formed to compensate livestock losses based on market value, nor was it intended as a ‘compensation’ scheme. Its aim was to test a conservancy-run process – local verification of claims and monitoring by conservancy committee and traditional authority. In addition, the authorization of payments for a type of ‘self-insurance’ is drawn from conservancy income to partially offset the losses of conservancy members versus the overall gains that wildlife brings to the conservancy (direct conservancy income and local jobs through tourism, trophy hunting, own use game harvesting). Conservancy committees and the support NGO, IRDNC, agreed on the amount to be refunded for animal losses before the scheme was started, initially using donor funding in the trial phases. The amount was deliberately kept low as it was acknowledged from the start that conservancies themselves would take over the repayments from their own income. Once the conservancy was used to its own income to finance the scheme, conservancy members could vote to increase amounts paid for predator losses. The crucial aspect, according to IRDNC, was that the process itself be tested and that the scheme be run by the conservancy, with Ministry of Environment and Tourism and IRDNC merely monitoring and providing assistance as needed. Compensation is based on this pre-determined amount that is less than the livestock value. However, the research reveals that respondents (n = 19) were dissatisfied with the amount paid (N$ 800-00 per ox killed), because they claim that the amount paid to relieve the immediate impact from wildlife is too little to sustain the affected member. In contrast, some respondents (n = 8) were satisfied with the amount paid as compensation. Despite criticisms about the amount paid for livestock losses, none of the respondents (n = 22) who were familiar with the scheme wanted it to be abolished. The respondents emphasized the need for the conservancy committee to review the amount paid as compensation, especially for cattle. They suggested an increase from the current N$ 800-00 to N$ 1000-00 per ox loss. The research reveals that community livestock management practices have not changed to deliberately benefit from the compensation. In fact community management strategies have improved because of the condition set by the review committee dealing with the compensation scheme. Wildlife incidents have increased because animals are habituated to techniques used by communities to deter them and this has contributed to high livestock incidents. For human-wildlife conflicts, the research acknowledges that the conflict exists. Between 2003-2005, the Kwandu Conservancy reported 1508 incidents of damage to crops by wildlife. Species that were responsible included elephants with 30.2 % damage, bush pigs (29.8 %), hippopotamus (12.7%), antelopes (12.7 %), porcupine (7.5 %), and baboons/monkeys (7.2 %). Most of the crops destroyed by crop raiders, as suggested by the respondents, were maize (30 %), sorghum (26 %), millet (17 %), groundnuts (14 %), pumpkins (8 %) and beans (5%). During the same period of crop losses, the conservancy reported 98 livestock incidents. Animals responsible for livestock incidents were crocodile with 32 incidents (32.7 %), then hyena (23 incidents, 23.5 %), leopard (22 incidents, 22.4 %) and lion (21 incidents, 21.4%). The role of community game guards was found to be extensive. From a total 35 responses, 74.3 % (n = 26) of members stated that community game guards effectively record incidents, chased problem-causing animals from the community crop fields by shouting or shooting in the air, and assessed or verified killed livestock for compensation purposes. In addition, community game guards conduct crop assessment for record-keeping purposes. The scheme for crop compensation is to be introduced in 2007. Currently there is no proper formula to use in assessing the value of crops and the method to use to compensate the affected members. Other methods used by communities to deter wildlife include sleeping in the field to guard crops, cracking a whip, construction of human statues, hanging tins on the fence, chilli coils, watchtowers and digging trenches. Respondents had different views on the best management practices for problem-causing animals. The response was generally based on the degree of threat that the animal posed. Most (43.8 %, n = 14) preferred the monitoring of problem-causing animals that are sighted in an area as a best practice, while 40.6 % (n = 13) of respondents preferred the animal to be captured and relocated to parks. Only 25.6 % (n = 5) of respondents preferred that the animal be destroyed. The management practices preferred by respondents when an animal kills a person are different from when an animal is simply sighted in the area. If an animal kills a person, only 12.5 % (n = 4) of respondents preferred that the animal be captured and relocated to parks, while 87.5 % (n = 28) of respondents preferred the problem-causing animal to be destroyed. None of the respondents suggested monitoring as the best management option for this degree of threat. In conclusion, the research revealed that Human Animal Conservancy Self Insurance Scheme does not treat the cause of the problem but the symptom. This approach does not decrease the level of the problem given that the cause of the problem is not addressed. Therefore, the researcher stressed the need to fully explore and implement the recent piloted lion, crocodile fencing, and elephant proof fencing and elephants chilli coil to address and reduce the problem within Kwandu Conservancy. In addition, the research revealed that the scheme has very lengthy delays before compensation is paid and the review panel does not arrange meetings on the stipulated dates. This causes a back-log in the number of claims that need to be reviewed and approved. On Human Wildlife Conflict the research findings recommend the need to strengthen and improve existing problem-causing animal management strategies that are in place. Innovative strategies include reducing the number of stray livestock at night and developing static fences. Communities should be advised, as is being done by IRDNC, to herd their livestock during the day and to build strong kraals. This is the most effective and cheapest way to prevent livestock from being taken by predators at night. Further more the research revealed that the combination and rotation of the methods yield high success rather than deploying a single method over a long period, for the prevention of crop losses methods include guarding the crop field, cracking a whip, shooting in the air, watchtowers, human statues and beating drums. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

This mini-dissertation is a comparison, by repeat survey, of farmer-related threats to cheetah (Acinonyx jubatus) survival on specific commercial farms in central Namibia. The research was conducted, to investigate if there had been changes in these threats to cheetah survival over a ten-year period (June 1991 to October 2001). A sub-sample of 31 farmers who were originally interviewed by the Cheetah Conservation Fund in June 1991, were re-interviewed between July and October 2001. These farmers were exposed to the Cheetah Conservation Fund awareness-raising programme. The results of this survey were compared to the results of the original survey of these farmers. This study showed that changes in farmer-related threats to cheetah survival have taken place. These include changes in land use, the attitude and behaviour of farmers towards cheetah, and cattle management practices. The land use changes include an increase in game farming, as a major source of income, by 19% of the farmers, since 1991. This increase in game farming was associated with an increase in game proof fencing and the introduction of alien antelope species into game fenced areas. The attitude of farmers towards the presence of cheetah on their farms was found to have changed significantly (p = 0.024), with 13% more farmers than before 1991 favouring cheetah presence on their farms. The behaviour of farmers towards cheetah has also changed in favour of cheetah survival. During the ten-year period from 1991 to 2001, 23% of the farmers removed no cheetah, compared to 10% for the ten-year period before 1991. Thirteen percent of the farmers were found to remove cheetah by trophy hunting only, as opposed to none prior to 1991. During the ten-year period from 1991 to 2001, the number of cheetah removed by the same farmers had declined by 243 (55%) cheetah when compared to the previous ten-year period. Game farmers were found to remove on average 3.75 times more cheetah than livestock farmers. Five game farmers were responsible for removing 92 cheetah, representing 47% of the total number of cheetahs removed. The majority (88%) of cattle farmers experienced calf losses to cheetah predation. In contrast to this, only 44% of smallstock farmers experienced losses to cheetah predation. The mean loss of livestock to predation by cheetah was found to be low, less than one animal per year for both calves and smallstock. The majority (73%) of cattle farmers implement only one livestock management strategy to prevent predation on calves by cheetah. The majority (88%) of smallstock farmers implemented more than one strategy to prevent predation. Changes in management practices to protect calves from cheetah predation since 1991 included a 14% decline in farmers using a technique known as 'calving camps' and an increase of 42% in the number of farmers monitoring their cows during the calving season. In conclusion, during the ten-year period from 1991 to 2001, both positive and negative changes in farmer-related threats to cheetah survival were recorded amongst the farmers interviewed. The positive changes include changes in the attitude and behaviour of farmers in favour of cheetah survival. However, this progress was tempered by change in land use from livestock to game farming, since game farmers pose a greater threat to cheetah survival than livestock farmers. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

Biodiversity losses are often influenced by humans due to increased demand over natural resources and retaliatory killing of wildlife as a result of human–wildlife conflicts. Large carnivores are in decline globally due to the current human–carnivore conflicts. This study was conducted in the Maasai steppe of northern Tanzania to understand the role of traditional husbandry techniques in reducing livestock predation, herding challenges that place livestock at risk for predation, willingness of pastoralists to participate in schemes for livestock security improvement, and the role of Tanzania National Parks (TANAPA) in mitigating human–carnivore conflicts. Data were collected using interviews with individuals in households and with herders in grazing fields and were reinforced with field observations. The primary husbandry strategies for livestock protection in homesteads were the bomas where livestock were enclosed at night, while in the grazing fields the strategies included: splitting livestock herds, herder among livestock, herder carrying weapons, and noise. There was no significant correlation between the wealth of an individual and the type of livestock protection strategy used at homesteads. All traditional strategies used by pastoral communities were equally ineffective in preventing livestock predation both at homesteads and in the grazing fields. However, over a four year period, there were no successful predations in any boma reinforced with chain-links, suggesting that reinforcing bomas with studier materials such as chain-link can be effective against livestock predation. Grazing in groups was found to provide more effective livestock protection in the grazing fields than any other strategy. While losing livestock by herders in the grazing fields contributed most to increased livestock predation, other herding challenges exposing livestock to predation included the seasonal nomadic lifestyle and long distances travelled by pastoral communities. The majority of respondents (91%) were willing to improve their livestock security by the use of chain-link fences at homesteads, while 87% were willing to participate in an insurance scheme for livestock security. Neither experience of livestock attack nor level of awareness of insurance scheme influenced willingness to participate in the scheme. There is growing awareness among pastoral communities of the benefits provided by carnivores and wildlife at large. Therefore, major conservation agencies such as TANAPA, Wildlife Division (WD) and other stakeholders should focus more than they have been on addressing the actual conflicts i.e. human–carnivore conflicts and helping to improve husbandry practices against predation to achieve conservation objectives by reducing retaliatory killing of carnivores.

Pulse-width modulation methods are widely used for the synthesis of ac voltages at the terminals of a voltage-sourced converter (VSC). Traditionally sinusoidal pulsewidth modulation (SPWM) has been used. A powerful alternative for this purpose is space-vector modulation (SVM), in which the converter is placed in a finite number of states in order to best approximate the reference voltage. This method offers better utilization of the dc bus voltage and provides several degrees of freedom for enhancement of the harmonic spectrum as well as switching losses. This thesis studies the SVM method for two- and three-level VSCs. A model for implementation of SVM in the electromagnetic transients simulation program PSCAD/EMTDC is developed. The model is able to generate firing pulses in linear as well as overmodulation range and is used to study the performance of different SVM strategies in terms of their harmonic spectra and associated converter and harmonic losses. The model is also used to demonstrate the suitability of the method for network applications. The thesis also employs genetic algorithms to find an optimized SVM sequence for improved harmonic performance. An objective function is defined that seeks to minimize the most significant harmonic components of the generated waveform, while keeping the other harmonic components within the acceptable range outlined in the available standards. The obtained sequence shows great improvement over the conventionally-used SVM sequence.

Modern industrial control systems use a multitude of spatially distributed sensors and actuators to continuously monitor and control physical processes. Information exchange among control system components is traditionally done through physical wires. The need to physically wire sensors and actuators limits flexibility, scalability and reliability, since the cabling cost is high, cable connectors are prone to wear and tear, and connector failures can be hard to isolate. By replacing some of the cables with wireless communication networks, costs and risks of connector failures can be decreased, resulting in a more cost-efficient and reliable system. Integrating wireless communication into industrial control systems is challenging, since wireless communication channels introduce imperfections such as stochastic delays and information losses. These imperfections deteriorate the closed-loop control performance, and may even cause instability. In this thesis, we aim at developing design frameworks that take these imperfections into account and improve the performance of closed-loop control systems. The thesis first considers the joint design of packet forwarding policies and controllers for wireless control loops where sensor measurements are sent to the controller over an unreliable and energy-constrained multi-hop wireless network. For a fixed sampling rate of the sensor, the co-design problem separates into two well-defined and independent subproblems: transmission scheduling for maximizing the deadline-constrained reliability and optimal control under packet losses. We develop optimal and implementable solutions for these subproblems and show that the optimally co-designed system can be obtained efficiently. The thesis continues by examining event-triggered control systems that can help to reduce the energy consumption of the network by transmitting data less frequently. To this end, we consider a stochastic system where the communication between the controller and the actuator is triggered by a threshold-based rule. The communication is performed across an unreliable link that stochastically erases transmitted packets. As a partial protection against dropped packets, the controller sends a sequence of control commands to the actuator in each packet. These commands are stored in a buffer and applied sequentially until the next control packet arrives. We derive analytical expressions that quantify the trade-off between the communication cost and the control performance for this class of event-triggered control systems. The thesis finally proposes a supervisory control structure for wireless control systems with time-varying delays. The supervisor has access to a crude indicator of the overall network state, and we assume that individual upper and lower bounds on network time-delays can be associated to each value of the indicator. Based on this information, the supervisor triggers the most appropriate controller from a multi-controller unit. The performance of such a supervisory controller allows for improving the performance over a single robust controller. As the granularity of the network state measurements increases, the performance of the supervisory controller improves at the expense of increased computational complexity. / <p>QC 20150504</p>

Power inverters, used to convert DC power to AC, are often used in e.g. solar power applications. However, they tend to be impractically large and expensive; as such, power miniaturization is an active research area. In this thesis, several classes of modern power inverters are evaluated and compared with regards to size, efficiency and output quality in order to identify areas of potential improvement. Methods for estimation of THD, power losses and input ripple are created and verified against a simulation of a five-level neutral-point-clamped inverter with SPWM control. Finally, this design is implemented physically and is found to achieve 94.5% efficiency and 7% THD under low voltage laboratory conditions, while remaining smaller than an average textbook.

The requirements on vehicle industry are constantly getting stricter, especially when it comes to emissions. At the same time cars, trucks and buses are needed for our way of living. This have forced companies to be as ecient as possible in their way of using fossil fuels for travelling and transport. To increase the eciency companies investigate all possible fuel savings to decrease their carbon footprint as much as possible. One area of savings that is not that obvious to many people is the alternator. Several percent of the total energy used by a vehicle are needed to operate the alternator. With a typical alternator eciency of 70% considerable savings can be achieved. This thesis that concern alternator eciency was carried out at Scania in Södertälje, Sweden. The goal of the thesis is to construct a mathematical model of an alternator. The model is supposed to consider all losses in the alternator and together with the output power give an eciency model of the alternator at different speeds and loads. A great part of the project has been dealing with the magnetic losses. The magnetic losses have been modeled as an equivalent circuit with the load angle as a central piece. The equivalent circuit is built up by the fact that the alternator used in the vehicles is a salient pole alternator. The equivalent circuit describes a voltage equation where the voltage drop over the magnetic inductance is described. From that relations between the signals in the alternator and output signals can be written. The alternator model is then used together with data recorded from different buses all over the world, this to be able to investigate how the alternator contributes to the fuel consump- tion depending on the way that the buses are driven. The result of this thesis is a mathematical model that describes the losses in the alternator for different load cases and speeds.