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The objective of this paper is to analyze the most up-to-date data available on total greenhouse-gas emissions of a LNG fuel supply chain and life-cycle of city gas 13A 1 based on surveys of the LNG projects delivering to Japan, which should provide useful basic-data for conducting life-cycle analyses of other product systems as well as future alternative energy systems, because of highly reliable data qualified in terms of its source and representativeness. In addition, the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 were also predicted, taking into account not only the improvement of technologies, but also the change of composition of LNG projects. As a result of this analysis, the total amount of greenhouse-gas emissions of the whole city-gas 13A chain at present was calculated to be 61.91 g-CO2/MJ, and the life-cycle greenhouse-gas emissions of LNG and city-gas 13A in 2010 could be expected to decrease by about 1.1% of the current emissions.

We evaluated total energy consumption and CO2 emissions in the phases of a city gas utilization system from obtaining raw materials to consuming the product. Assuming monthly and hourly demand figures for electricity, heat for space heating, and hot water in a typical hospital, we explore the optimal size and operation of a city gas system that minimizes the life cycle CO2 emissions or total cost. The cost-effectiveness of conventional cogeneration, a solar heating system, and hybrid cogeneration utilizing solar heat is compared. We formulate a problem of mixed integer programming that includes integral parameters that express the state of system devices such as the on/off condition of switches. As a result of optimization, the hybrid cogeneration can reduce annual CO2 emissions by 43% compared with the system without cogeneration. The sensitivity of CO2 reduction and cost to the scale of the CGS is also analyzed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 22–32, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10369

Efficiency and CO 2 emissions between various methods of biomass energy conversion are compared from the viewpoint of life-cycle evaluation. As for electricity generation, efficient processes are thermal gasification combined cycle, supercritical water gasification combined cycle, and direct combustion in order of efficiency for low moisture content biomass. Supercritical water gasification combined cycle is the most efficient for high moisture content biomass. Battery electric vehicle, gasoline hybrid electric vehicle, and gas full cell vehicle (FCV) show high efficiency in automobiles. Biomass FCV shows high efficiency in the vehicles utilizing biomass. Biogas combustion is the most efficient for heat utilization. Then, the position of supercritical water gasification in various technologies of energy conversion is examined by modeling an overall energy system. The tradeoff between CO 2 emissions and total cost of technologies is analyzed so that the most cost-effective technology can be determined for different CO 2 emissions constraints. Computed results show that biomass is mainly consumed for electricity and heat generation so as to utilize finite biomass resources efficiently. Transportation fuels are generally made from fossil fuels. Cost-effective processes for CO 2 reduction are thermal gasification and reforming when the present efficiency and prices are assumed. Supercritical water gasification is also one of the optimal processes when the relative cost to fuel cell decreases. Improving heat exchange efficiency also contributes toward enhancing the position of supercritical water gasification in biomass technologies.

We evaluate total energy consumption and CO2 emissions in the phase of the city gas utilization system from obtaining raw materials to consuming the product. First, we develop a simulation model which calculates CO2 emissions for monthly and hourly demands of electricity, heats for air conditioning and hot-water in a typical hospital. Under the given standard capacity and operating time of CGS, energy consumption in the equipments is calculated in detail considering the partial load efficiency and the control by the temperature of exhaust heat. Then, we explored the optimal size and operation of city gas system that minimizes the life cycle CO2 emissions or total cost. The cost-effectiveness is compared between conventional co-generation, solar heat system, and hybrid co-generation utilizing solar heat. We formulate a problem of mixed integer programming that includes integral parameters that express the state of system devices such as on/off of switches. As a result of optimization, the hybrid co-generation can reduce annual CO2 emissions by forty-three percent compared with the system without co-generation. Sensitivity for the scale of CGS on CO2 reduction and cost is also analyzed.

In this paper, we proposed a procedure for calculation of room temperature in multi-room building using the backward-difference method. Based on this procedure and using our simulation program, we evaluated CO2 reduction by installating high light-reflective and high heat-emissive paint in buildings. Heat balance equations on each heat point in each room or wall in the building were deduced from one-dimensional heat-conduction equation and converted to the matrix equation. We improved matrix computing and developed a different procedure from conventional methods. Because this procedure is simple, we consider that this is applicable to estimation of most building’s technologies. As its application, the effects of high light-reflective and high heat-emissive paint was evaluated. Although the paint increases heating load, it can reduce cooling load. We thus conclude that the paint is effective for CO2 reduction.

The dispersion of input-coefficients in input–output (I–O) tables and the effect on LCA results are evaluated, utilizing the data for compiling the I–O tables. CO2 emission intensity and its variance with each commodity and service categorized in the I–O tables are estimated and applied to the LCA of a specific passenger car. Calculated results show that coefficients of variation (CV) of CO2-emission intensity are about 0.8 for the intermediate commodities which are frequently assessed in LCA. CO2 emissions induced by the production of the passenger car and the CV of the emissions are estimated at 1.3 Mg–C and 0.14, respectively. The value of CV is smaller than that of the most intermediate commodities since the CV of total emissions decreases as the number of components of the passenger car increases. Although emission intensity itself given by I–O tables has large variance, I–O tables are still useful tools for LCA if the number of components of a product is large enough.

Summary The evaluation of tradeoffs between technologies and policies for mitigation of environmental problems requires a systematic investigation of effects over the entire region under consideration. When attempting to model such large complex systems, issues such as usability, maintenance, and computing efficiency often become major modeling barriers. In this work a software prototype for integrating the services of computational models over the Internet, called DOME (distributed object-based modeling environment) is used to facilitate the construction of virtual Tokyo—a simulation platform for evaluating holistically the tradeoffs between various technologies for reducing the emissions of greenhouse gases. In making steps toward this ultimate goal, two models have been developed that use data defining spatial land-use distributions and the flows of goods expressed as an input-output table to provide information on the spatial and temporal characteristics of an urban region. Integrated, these models form a preliminary virtual Tokyo model when applied to Tokyo-specific databases. Given this platform, process models are applied to examine the effectiveness of using photovoltaic (PV) modules on the demand side to reduce conventional electric power generation and, thereby, also reduce carbon dioxide emissions. The results of introducing PV modules on the rooftops of buildings in Tokyo under various installation conditions are presented as a working example of the prototype. For full deployment on usable rooftop space, PV power generation could reduce carbon dioxide emissions from electric power generation by more than 12%. Future work will use the same methods as presented in this paper to examine cost, a critical determinant in the actual feasibility of PV module installation.

An analysis was conducted on greenhouse gas emissions from the liquified natural gas (LNG) chain and life cycle of City Gas 13A [caloric value: 46 MJ/Nm3(11,000 kcal/Nm3)], which is produced from LNG. The analysis was based on highly reliable data which are qualified in terms of source and representativeness. Actually, the latest data for CO2 and CH4 emissions from the natural gas field and liquefaction plant were obtained from field studies. Moreover, the analysis includes CO2 emissions during the LNG transportation from exporting countries to Japan, city gas production and distribution stage in Japan and the manufacturing of facilities associated with the production of natural gas overseas to final domestic consumption. The reduction effect of CO2 using LNG cryogenic energy was also considered. The evaluation showed that the level of greenhouse gas emissions and energy consumptions in the modern natural gas production and liquefaction plants were lower than those previously reported due to improvements in the production process. The results of the analysis also provide basic data essential for conducting life cycle analyses in many fields using natural gas.

After COP3 a lot of countries and even their local governments are struggling to reduce CO2 emissions. However, the way to define CO2 emissions is not consistently standardized. In this study we calculate CO2 emissions in two ways: appar-ent and responsible emissions. Apparent CO2 emissions are caused by the domestic industrial activities and they include CO2 embodied in exports. Responsible CO2 emis- sions are attributed to domestic final demand and they include CO2 embodied in imports. We classify domestic production into that of Tokyo and that of the other regions, and cal-culate regional CO2 emissions by the above two ways. From the viewpoint of LCA (Life-Cycle Assessment), we utilized the regional input-output table for the database. Apparent and Responsible CO2 emissions of Tokyo are 17 Mt-C and 32Mt-C, respectively. Because the amount of CO2 results in such different values, standardizing the way to define CO2 emissions is a critical problem for deciding the goal of CO2 reduction. Concerning the emissions in each sector, power generation and transport have the largest reduction potential in industrial sectors. Making the life of buildings longer is the most effective measures from the consumers' viewpoint.

Degradation of the global environment and depletion of resources are threatening sustainable development of mankind. In particular, climate change caused by increasing greenhouse gases is one of the most serious issues in analyzing energy systems. This paper aims at proposing frameworks to investigate sustainability and at evaluating technologies for sustainable energy systems. For this purpose, we first define the index of sustainable limits on resource depletion and emissions. Sustainability of mineral and energy resources is evaluated based on the index. Estimations indicate that energy resources and CO2 are unsustainable, and that we should introduce technologies to reduce energy consumption and CO2 emissions. Life cycle energy requirements are assessed for photovoltaic systems as representatives of the technologies. Through the life cycle assessment, we quantitatively evaluate measures to improve life cycle energy requirements and capital costs. At the same time, we clarify the direction of research and development required for technologies to realize sustainable energy systems. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 25–31, 2000

This paper deals with sustainable energy technologies under restrictions on resources and environmental impact. We have developed a database to estimate life-cycle efficiencies and greenhouse-gas emissions. Next, we define sustainability limitations on resource depletion and emissions. Based on these concepts, the present world energy system is judged to be unsustainable. Mitigation measures such as disposal of CO 2 and solar power generation are evaluated utilizing the concept. We show how sustainability influences the cost-effectiveness of measures taken.

This paper deals with sustainable energy technologies under restrictions on resources and environmental impact. We have developed a database to estimate life-cycle efficiencies and greenhouse-gas emissions. Next, we define sustainability limitations on resource depletion and emissions. Based on these concepts, the present world energy system is judged to be unsustainable. Mitigation measures such as disposal of CO 2 and solar power generation are evaluated utilizing the concept. We show how sustainability influences the cost-effectiveness of measures taken. At the same time CO 2 removal is shown to play a transitional but important role to realize sustainable energy scenario in ultra-long term.

This paper aims at clarifying key points for realizing sustainable energy supply under restrictions on resource and environment. For this purpose, we first developed a database to estimate life cycle efficiencies and greenhouse gas emissions for various energy systems. Then on the basis of this life cycle assessment, we quantitatively define the concept of ‘Sustainability Limitations’ on resource depletion and environmental emissions. From this concept, present world is judged to be unsustainable both from resource and environmental viewpoints. At the same time, we clarify how far present world is from Sustainability Limitations. Then we describe our mathematical model simulating global energy supply and demand in ultra-long term. In this model, the concept of Sustainability Limitations is utilized so as to impose economic incentives to make energy system shift to a sustainable one in long term. Sustainability limitations of resource depletion and CO2 emissions are taken into consideration. As energy resources, this model includes coal, oil, natural gas, other unconventional fossil fuels, uranium and renewable resources. As energy technologies, it includes major technologies of mining, transport, conversion and final utilization. Computed results have shown that present energy system, which is judged to be unsustainable, shifts to a sustainable system in the ultra-long term with appropriate incentives.

Depletion of the fossil fuels and climate change caused by the greenhouse effect is threatening the sustainable development of mankind. Since the CO 2 produced by burning fossil fuels is the dominant source of anthropogenic greenhouse gas emissions, CO 2 disposal is expected to be an effective option for mitigating climate change. However, if we took the option of CO 2 disposal and continued relying on fossil fuels, it could not be the sustainable use of energy resources. Therefore we need some theoretical framework for realizing the sustainable development. In this paper, we have developed a model to demonstrate the way of sustainable use of energy resources under constraints on CO 2 emissions. Computed results have shown that present energy system based on fossil fuels shifts to the system based on renewable resources in the ultra-long term with appropriate incentives. CO 2 disposal plays an important but a transitional role in this analysis.

In this paper we have investigated the modification of energy system for reducing CO 2 economically. Hydrogen production plants with CO 2 removal systems and cogeneration plants are key technologies to reduce CO 2 economically. Characteristics of a novel energy system, which includes energy plants as described above, has been investigated with a linear programming model. A reference system has also been represented which behaves similarly to the present energy system for comparison. Static analyses of the models has demonstrated that CO 2 emissions can be reduced more economically and efficiently in the novel energy system than in the reference system. Dynamic analyses has shown the processes of the transitions from the present energy system to the novel energy system.

The future demand for electricity is uncertain and difficult to forecast, but it is necessary to do so in order to construct power plants. In that sense, a large-scale power plant is disadvantageous because it takes a long time to construct. On the other hand, although it takes less time to construct, a small-scale power plant is more expensive. Therefore large- and small-scale power plants could complement the disadvantages of each other. This paper develops a stochastic dynamic programming model to investigate the possibility. The model determines the capacities of large- and small-scale power plants in the face of uncertain demand to minimize the expected value of the total cost. Computed results have shown that small-scale plants can play a significant role in this case even if they are more expensive than large-scale plants.

Publisher Summary Transportation is the basis of economic and social activities, which are indispensable for our human life. On the other hand, a large amount of energy is consumed through transportation, such as motor cars. This results in an increase in environmental emissions such as CO 2 , which contributes towards global warming. It is necessary to establish transportation systems with low environmental burdens, properly according to the growth in traffic demands and the needs of users. There are many countermeasures to reduce CO 2 emissions in the transportation sector. Among them, modal shift has not taken effect widely, although its necessity has beenrecognized in the past. While encouraging modal shift, it is the characteristics and transportability of substitutes for conventional means of transport that count. Under these circumstances, taking encouragement of modal shift in the passenger transportation sector into account, the authors have focused upon electric trolley buses (ETBs) as one of the substitutes for motor cars. This chapter aims to make an environmental evaluation of the ETB system. Initially, CO 2 emissions from ETBs, when driven under urban traffic conditions, were estimated and subsequently estimated from the viewpoint of life cycle assessment (LCA) to compare with those from other public transportation systems. Finally, an environmental evaluation in urban motor traffic system was carried out on the condition that ETBs be introduced as substitutes for diesel route buses. Results conclude that ETBs is one of the promising public transportation systems for establishing a transportation system with low environmental burdens, by encouraging modal shift in the passenger transportation sector.

Publisher Summary CO2 emissions from the commercial and residential sectors have greatly increased in Japan. Governmental regulations for energy saving are very effective for the industrial sector, but they are found to be rather ineffective for the commercial and residential sectors. Thus, low-cost measures for CO2 reduction are really required in these two sectors. This chapter focuses on the installation of outer skin surface technologies to buildings. These technologies, low-cost measures for CO2 reduction, are applicable to buildings that have high light-reflective and high heat-emissive paint and the low light-reflective and the low heat-emissive outer skin surface. The air-conditioning demand in the building is calculated according to the recently developed dynamic heat load simulation program, and assesses the extent of reduction in CO2 emissions brought by high light-reflective and high heat-emissive paint or low light-reflective and low heat-emissive outer skin surface.

In this paper, we have investigated the cost-effectiveness of alternative fuel vehicles as a measure for CO2 reduction. Computed results indicate that the installation of alternative fuel vehicles is much more expensive than fuel switching in industry or the power generation sector. However, some economic incentives will make the price go down to the level at which alternative fuel vehicles are competitive with conventional vehicles. At the same time, mass production makes their prices go down although it is rather expensive at present. Then, we developed the scenarios in which CO2 emissions could be stabilised at the level in 1990. In the higher demand case (1.2%/yr.), it is indispensable to introduce alternative fuel vehicles into the market. Our model selects electric vehicles and compressed natural gas vehicles as cost-effective options. In the scenario where carbon tax revenue is not offset by subsidy, we have to impose prohibitively high carbon tax to suppress CO2. However, CO2 emission can be suppressed by a reasonable carbon tax if the tax revenue is returned to the market to subsidise alternative fuel vehicles and their infrastructures.

This paper aims at evaluating technologies to realise a sustainable energy system within the constraints of resources and environment. For this purpose, we first developed a database to estimate life cycle efficiencies and greenhouse gas emissions for various energy technologies. Then, on the basis of this life cycle assessment, we quantitatively define the concept of sustainability limitations on resource depletion and environmental emissions. From this concept, the present energy system of the world is judged to be unsustainable from both resource and environmental viewpoints. Then, various mitigation measures such as disposal of CO2 and solar power generation are evaluated utilising the concept. The evaluated result showed how sustainability influences cost–effectiveness of the measures. At the same time we clarified the key points to realise a sustainable energy scenario in ultra–long term.

In recent years, human activities have begun to seriously influence local and global environments. Under the circumstances, Life Cycle Assessment (LCA) is expected to be a powerful tool in evaluating impacts on environments. However, LCA is not yet established methodologically or formulated systematically. The main problems are: 1. Estimation of the repercussions of the activity of a main product on others. 2. Allocation of resource consumption or emission between a main product and recycling or cascading products. 3. Allocation of resource consumption or emission between a main product and co–products in a combined production. In this context, we have developed novel LCA procedures using linear programming (LP), an allocation method using the best base inverse matrix of LP (BI–allocation) and investigated passenger cars as an example. As a result of these procedures, the repercussion effect and allocation problems are systematically calculated and it is proved that BI–allocation makes a system more suitable than allocation by product weights.

For a traffic control of ships passing the control region arbitrarily, optimization techniques can be utilized to get smooth and safe courses avoiding dangerous encounters where miss distance and destination error for each ship are evaluated as a criterion function. To realize such optimal course selection, however, reliable communication systems are indispensable, because ships may take the nearest courses just beyond the miss distance.In the paper, a communication system using conventional marine radars is proposed to realize mutual communication between ships and/or the control station. In the proposed system, control information such as position or velocity of each ship is broadcast to surrounding ships by PPM (pulse position modulation) of radar pulse with dual-k convolutional coding. The information is broadcast, divided into 4 subframes corresponding to each scan of the radar antenna, and those subframes of different radars are identified by detecting the preamble uniquely specified to each radar. The data of 80 bit length can be broadcast within 20 seconds using conventional radars.Use of the coding technique as well as the PPM ensures reliability of the communication, enabling each receiver to separately extract correct information of other ships in heavy radio interference environment. The applicability of the system is evaluated for the situation investigated in the previous papers. From the investigation, it is shown that the overall error rate of the communication system, taking account of false preamble error and decoding error, is less than 10-5 over 99.99999% of the total time, which is regarded sufficient for such purposes.

The overall guidance and control system with the Spin Free Analytic Platform (SFAP) type attitude reference that is used for the M-3S rockets that launched Japanese Scientific Satellites, is shown with detailed description for the function of each composing unit, and results of evaluation from actual flight experiments are also shown. The SFAP attitude reference system is provided with two RIGs for pitch and yaw mounted on a roll stabilized platform, on which also mounted a roll RIG compensating the coning effect arising on the platform using the signal fed back to a Roll RIG torquer from the output of Digital Differential Analyzer (DDA) which calculates pitch and yaw angles in strapdown mode. This also makes it easy to correct reference attitude angles by radio commands from a ground tracking station. Specified performance of drift rate of the overall system is within 0.5°/min. From experimental results, it was assured that this value was realized for more than 5 flights. Some results of actual flight experiments are also shown.

A three dimensional attitude control system for a streamlined cruising type autonomous vehicle are studied. A streamlined vehicle are appropriate for deep sea investigation in a wide area for its high efficiency of energy consumption, converting potential energy to velocity energy. Authors studied a simple altitude control system for such autonomous vehicle, based on distance observation by four ultrasonic fan beams to differeat directions. The system is based on two dimensional pitch control, and if it is applied to this type of vehicle, it is shown that interference between yaw and pitch motion causes serious velocity decrease by large sideslip angles due to small lift in the side direction. In the paper, effective three dimensional attitude control method based on so-called Bank-to-turn control, which is named. Roll-Pitch-Roll control in the paper, is proposed. And the system performance is investigated by simulation study for various cases, from which the following results are obtained.(1) For large yaw angle rotation, RPR control improves rotating speed remarkably without decreasing cruising velocity, which can be hardly realized when each axis is controlled independently due to the motion interference.(2) Improvement of speed decrease for large rotation angles both in yaw and pitch direction.From these results, it is concluded that the proposed system is utilizing strong lift force in pitch direction effectively, and appropriate for attitude control for this energy saving type cruising vehicle with asymmetric shape.

A simple radio guidance system was adopted for M Series rockets that are used to launch Japanese scientific satellites, because of its cost performance and for orbital accuracy. In this paper, the basic concepts of the radio guidance system and its algorithm are shown with the flight plan of the rocket. The idea is simple and straightforward. As a consequence, the software is reliable and the capacity of the computer is not exceeded, and yet the guidance system still achieves the required accuracy. The system has been implemented gradually and with success during the last ten launchings. Improved accuracies were realized. In this paper the algorithm is described and several of the resulting trajectories are shown.

Authors have been studying a guidance and control system for an autonomus underwater vehicle of a streamlined cruising type, which is appropriate for deep sea investigation in a wide area for its high efficiency of energy consumption, and it does not need safety equipment for human operators. However, in the unmanned control, real time utilization of visual information for control and other decision making, which is a major advantage of human operation, is difficult at present.In the study, basic methods to estimate motion or attitude of the vehicle (camera) from video data which is obtained continuously by a video recorder and/or a camera are investigated, and several alternative methods to estimate the vehicle motion are evaluated by actual sample pictures. Finally, possibility of the motion estimation from visual information is investigated by applying those methods to actual underwater video images.From the study, it is assured that estimation of camera motion (ego motion) from usual landscape pictures is possible by simpler and quicker methods. on the other hand, it is not so easy at the sea bottom, for there are few landmarks and visual pattern does not change clearly. However, by using full information and selecting appropriate estimating points, possibility of the motion estimation at the sea bottom is assured for the case human operator can recognize the motion visually.

In usual regional models for long range planning, the objective areas are divided into a reasonable number of subregions, in which there still remain inequalities of spatial distribution of human activity levels. In the paper, a model to express geographical distribution of population in a region is proposed to extract essential information from the grid data for a desirable allocation of infrastructures or other investments, the geographic relations of which influence their efficiencies or conveniences in the region. The model is used to evaluate regional policies about the allocations of such facilities. A concept to utilize such information to compensate conventional regional planning are also proposed

Robotization in Japanese manufacturing industries has grown rapidly and steadily in the last ten years supported by labor shortage pressure, adaptation of process lines for robotization, and improvement of reliability and cost performance of cheaper and simpler robots available for automation of simple process lines. At the same time, robotization has been a significant factor in the increases in productivity and has been of particular benefit to the electric and automobile industries in the international market place. Taking account of these situation, Japan is a good place to study the socioeconomic implications of robotization, and a project was commenced within the Japan Institute of Policy Science with this purpose in mind, aiming at a quantitative analysis of robotization as an economic process and it's economic impact. This paper presents an overview of the present status of robotization and examines possibilities for future development, focusing mainly on the above two industries which have so far been the main robot users. And the ways that robots have been used, incentives for robotization and the accompanying problems will be described in chronological order up to the present. The major data base of this paper is results of a survey by the Japanese Industrial Robot Association based on a wide ranging questionnaires sent to both robot users and producers, and results of interviews with engineers mostly from within the electrical and automobile industries.

Summary The attitude control system whose attitude reference is established by a 2-degree-of-freedom gyroscope (2-DFG) mounted on a single axis stabilized table has been developed to launch Japanese scientific satellites by Mu rockets. Firstly the final attitude was only specified by the rotor of 2-DFG, while now the function is augmented to include the pitch programmer and the radio guidance receiver. Then this system was applied to Mu-3C rockets whose 2nd stage motor is stabilized by liquid injection thrust vector control (LITVC) unit, and realized successfully two satellites. For the past successful 7 flight experiments, the trajectory estimation based on the iterative least square (differential correction) method gave very satisfactory results. From these analysis, it is concluded that the injection errors of total system were within the 2° in pitch, 5° in yaw and 1% in velocity.

At the docking of a three-dimensional moving vehicle to a fixed base in deep water, an automatic system is indispensable to assure reliable and safe operation, and authors proposed an automatic docking system using ropes for such situation. In the first report, the investigation was focused on the practical feasibility of real time state estimation which is the most significant at the docking, and it is shown that a near optimum filter can be effectively utilized to estimate the state variables of the moving vehicle, based on which the vehicle can be controlled by the ropes.In the first report, proportional control law was applied to check controllability of the system by the ropes, although it is not sufficient for the docking which requires accurate access to the docking point along the desirable trajectory avoiding collision or unexpected oscillations. Therefore, an optimal control technique is introduced to improve control performance of the system, and practical feasibility, especially that of real time computation is investigated.Considering the system requirements and computational feasibility, the system equations are linearized and linear regulator algorithm is applied for the docking control. The system performance is investigated by simulation study, and the following results are obtained.1) Proposed control algorithm based on the optimal regulator can control the system fast and stably compared with the proportional control law by selecting adequate control parameters through the simulation study.2) It is shown that real time control by conventional mini-computers is possible if only there are enough memory capacity for storing feedback control coefficients computed in advance. The off-line optimizing computation is not so difficult for this problem formulation, and it can be also computed by a small computer.3) The system can control the vehicle stably when it approaches within ±5×5 m area in horizontal plane and 10 m above the base. This is easily realized by conventional control system using ultrasonic positioning systems.4) When the vehicle is controlled based on the filter outputs, i. e., estimated state variables, overall control accuracy of the system is the same order as the filtering accuracy, which is sufficient for the docking requirements.

A guidance and control system for an autonomous vehicle of a cruising type with a rudder and elevator is studied, which is intended to investigate the surface of ocean ground continuously. In order to collect underwater information continuously taking pictures or measuring chemical characteristics, it is required to keep low altitude from the surface on the condition that it keeps the safety distance.In the paper, a simplified altitude control system to keep predetermined height is investigated observing the distances to the surface by several narrow ultra sonic fan beams in different directions. The control system is consist of two hierarchical control blocks, i. e. a guidance block to give attitude reference angle calculated from the observed distances to keep desirable altitude, and a local attitude control block to realize the reference angle keeping the stability of the vehicle. As the attitude control system, a linear feedback elevator angle control system with velocity saturation is adopted, taking account of the system dynamics.In the guidance block, pitch correction angle is calculated from the observed distances. Three different algorithms, linear, polynomial filtering, and mixed type, are proposed. And the system performance of each is evaluated from various surface conditions by simulation study using simplified two dimensional model in vertical (pitch) plane. Non-symmetric smoothing of the correction angle is also introduced to keep the safety distance for rough surfaces. From the study, it is assured that the proposed control system can control the vehicle to keep the predetermined altitude for most cases within 20% margin, and basic feasibility of the system is verified.

For a long range prospect of energy demands, improvement of fuel economy(FE) of cars is an important factor because it is not easy to substitute gasoline demands by other energy resources. Although recent FE for a standard running pattern has been remarkably improved, FE in real use depends on actual running patterns in cities, and there are some discrepancies between actual and the standard FE. Therefore, to improve accuracy of energy demands prediction, quantitative analysis of running patterns and their effects on FE is required, and authors measured actual running profiles for various road conditions by developing a simple measurement system, from which basic running patterns in cities are obtained. Then a model to estimate FE from the data is developed, and effects of present city running on FE are analysed quantitatively with the model, which can be used to evaluate future changes of FE in real use.

This article aims at estimating life cycle CO2 emissions from electric vehicles (EV) and gasoline vehicles (GV), although the estimation in this study is not an LCA according to ISO14040s. For this purpose, a mathematical tool called the Process-relational model was developed. The Process-relational model is used for establishing life cycle inventories. The model has a structure which improved the principle of input-output analysis in econometrics that only one product is generated by one process. This model enabled us to overcome difficulties of LCA in retracing complicated repercussions among production systems.