京都大学 / 新制・課程博士 / 博士(工学) / 甲第24146号 / 工博第5033号 / 新制||工||1786(附属図書館) / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 藤本 健治, 教授 松野 文俊, 教授 森本 淳 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Whether insiders can use informational advantage when purchasing or selling their company stocks to generate cumulative abnormal returns (CAR) has shown different results in several markets. The Swedish market is yet to be extensively examined, and this thesis aims to understand how insiders in the OMXS30 companies perform when testing CAR and if there exists an information asymmetry. A predicted return is generated through the market model to calculate CAR, and the same index OMXS30 is combined with stock return data. We conducted an event study through Stata to match the transactions with a particular trading day to see how the insiders' transaction yielded CAR. We find that significant CAR exists for all insider groups for various event windows and find a difference in significant CAR for both genders and insider positions. The results were robust when we changed to a new market index as the independent variable in our regression analysis. The results align with previous literature, stating that insiders generated significant CAR from insider trading and differences between insider position and gender (Jeng et al. 2003; Jiang & Zaman, 2010; Lasfer & Ye, 2023). The findings can be used for regulatory purposes when investigating information asymmetry.

This study addresses the empirical question of heterogeneous market efficiency characteristics, specifically as they are attributable to divergent levels of professional securities analyst attention. As a significant group of information intermediaries, analyst institutions conceivably influence, in a profound manner, the efficiency with which security prices respond to new information. Consistent with this notion is the hypothesis that the securities of firms which are neglected in terms of analyst coverage exhibit price inefficiencies relative to their closely followed counterparts. Two market efficiency constructs with respect to annual earnings announcements are examined in this study. Preannouncement information efficiency is guaged by the degree to which security prices appear to lead or anticipate the information content of subsequent public earnings releases. Such price behavior is indicative of the market's ability to acquire and, process interim, signals that are relevant to the determination of proper and timely security valuations. Postannouncement, or semi-strong-form, efficiency is in turn referenced by the relative absence of anomalous "drifting" patterns in postdisclosure returns. The presence of significant drifts is inconsistent with a market that adjusts quickly and unbiasedly to signals that are transmitted publicly. Sample firms taken from the NYSE are ranked into three groups according to their relative following by the professional securities analyst community. Analyst attention is surrogated by the number of investment houses providing annual earnings per share forecasts for companies listed in the Institutional Brokers Estimate System (IBES) computer file. The delineation of the three attention concentration groups' relative efficiency profiles is accomplished by means of two uniquely derived metrics that restate cumulative abnormal returns (CAR's) into an ordered domain of pre- and postannouncement efficiency structures. The CAR's are derived from dailly price data immediately surrounding annual earnings announcement dates for the calendar years ended 1976 through 1982. Owing to the nonnormal distributional properties of the inefficiency metrics, two nonparametric procedures are employed to detect group mean differences. The results overwhelmingly indicate that both pre- and postannouncement efficiency are positively associated with professional analyst attention. Moreover, the detected efficiency differences cannot be attributed to firm size effects or to the extent of the market's forecast error -- two factors that have previously been established in the empirical literature to be associated with event period CAR magnitudes. / Ph. D.

The first focus of this thesis is a basic scientific research in the field of super-regenerative receivers (SRRs) and, in particular, super-regenerative oscillators (SROs). In chapter 3, a theoretical analysis of SROs is performed and its nonlinear behavior is studied in both time and frequency domains. The cross-coupled architecture is studied as a special case, however, widely used topology in the SRO design. The start-up and decay envelopes of the oscillator output are studied in relation to the input. The SRO start-up time and the maximal achievable quenching frequency are investigated. For phase modulation purposes, the relation between the initial phases of the input and output signals is investigated. In addition, a frequency-domain analysis is performed to ease the characterization of test circuits at high frequencies where time-domain measurements are not possible. The analytical results are verified by circuit-level simulations and measurements of a 2.4-GHz SRO. This study provides design guidelines for the design of SROs and helps in determining the optimal system parameters when targeting both amplitude and phase modulations. The SRO concept and its phase sampling capability are further studied in chapter 4. For this purpose, two SRO circuits operating around 60GHz are investigated, designed − in both CMOS and SiGe BiCMOS technologies − and characterized. Different circuit techniques are studied in order to improve the energy efficiency and maximize the switching speed. For instance, a novel quenching technique to maximize the power efficiency is presented. This circuit approach includes a pulse generator, which generates the quench signal allowing to switch the SRO with a minimum duty cycle. In fact, the SRO input is sampled at the onset of oscillation and, therefore, it is unnecessary for the oscillator to run for a long time in its steady state. This allows to minimize the on-time of the SRO and to considerably reduce its power consumption. Compared to the state of the art, the circuit achieves by far the highest power efficiency of 21.7%. In addition, a novel switching scheme is presented in order to maximize the quenching speed. This approach enables to greatly reduce the switching time constant, allowing to improve the SRO quench rate by approximately a factor of 3 compared to the state of the art. A record switching frequency of up to 10GHz is achieved. The second focus of this thesis is the investigation of on-off-keying (OOK) receivers operating at a carrier frequency of 60GHz. OOK modulation schemes have the advantage of low circuit complexity and, therefore, low power consumption and small chip area. The drawback of low spectral efficiency can be mitigated by the large bandwidth at mm-wave frequencies, in particular, at the 60-GHz ISM band, 9GHz from 57 to 66GHz, which allows to achieve high data rates. The goals of this study are enhancing the speed, maximizing the energy efficiency and improving the sensitivity. For this purpose, several circuit approaches are studied. A highly efficient envelope detector and a novel limiting amplifier architecture with simultaneously large bandwidth and high gain ensure high-speed low-power operation. A high-gain low noise amplifier is employed to increase the sensitivity. A feedforward dc-offset cancellation technique is used to ensure the proper operation of the receiver. As a proof of concept, the chips are implemented in a 130-nm SiGe BiCMOS technology. The OOK receiver achieves a record data rate of up to 20Gb/s at a bit-error-rate less than 10^(-12). The low power consumption and the ultra high speed capability allow a highly energy-efficient operation of only 2.2pJ/bit. Finally, this thesis studies the design of 60-GHz amplifiers. In fact, one of the main challenges of transmitting data at mm-wave frequencies is the high free-space path loss, which limits the transmission range. To alleviate this issue, amplifiers with high output power at the transmitter side and with low noise figure and high gain at the receiver side are required. Chapter 6 investigates the design of a low noise amplifier (LNA), with the study focus being achieving simultaneously large bandwidth, high gain, low noise figure and low power consumption in order to enable a high-speed receiver with high power efficiency and high range. The LNA achieves a bandwidth of 23GHz, a gain of 23.8dB and an average noise figure of 3.2dB and consumes only 8mW, remarkably improving the state of the art. In addition, this chapter presents the investigation and design of a 60-GHz power amplifier with an output power of up to 14.7dBm and a small chip area to ensure a sufficient communication range at the transmitter side.

Recent advances in wireless communications along with developments in low-power circuit design and micro-electro mechanical systems (MEMS) have heralded the advent of compact and inexpensive wireless micro-sensor devices. A large network of such sensor nodes capable of communicating with each other provides significant new capabilities for automatically collecting and analyzing data from physical environments. A notable feature of these networks is that more nodes than are strictly necessary may be deployed to cover a given region. This permits the system to provide reliable information, tolerate many types of faults, and prolong the effective service time. Like most wireless systems, achieving low power consumption is a key consideration in the design of these networks. This thesis presents algorithms for managing power at the distributed system level, rather than just at the individual node level. These distributed algorithms allocate work based on user requests to the individual sensor nodes that comprise the network. The primary goal of the algorithms is to provide a robust and scalable approach for tasking nodes that prolongs the effective life of the network. Theoretical analysis and simulation results are presented to characterize the behavior of these algorithms. Results obtained from simulation experiments indicate that the algorithms can achieve a significant increase in the life of the network. In some cases this may be by an order of magnitude. The algorithms are also shown to ensure a good quality of sensor coverage while improving the network life. Finally, they are shown to be robust to faults and scale to large numbers of nodes. / Master of Science

Yes / The paper presents a new cluster based routing algorithm that exploits the redundancy properties of the sensor networks in order to address the traditional problem of load balancing and energy efficiency in the WSNs.The algorithm makes use of the nodes in a sensor network of which area coverage is covered by the neighbours of the nodes and mark them as temporary cluster heads. The algorithm then forms two layers of multi hop communication. The bottom layer which involves intra cluster communication and the top layer which involves inter cluster communication involving the temporary cluster heads. Performance studies indicate that the proposed algorithm solves effectively the problem of load balancing and is also more efficient in terms of energy consumption from Leach and the enhanced version of Leach.

No / Tank flooding have become major causes of pollution both in residential and industrial areas majorly caused by overflows of water(mostly residential) and volatile poisonous industrial liquids from the storage tanks. An effective way of avoiding this problem will be by deploying some mechanism to monitor liquid level at each point in time and escalating unusual liquid levelsto a pump control circuit or to the relevant authorities for prompt action to avoid a flooding occurrence. This paper presents a low cost power efficient liquid level monitoring technique. Passive RFID tags are designed modelled and deployed, the signal variation from the Alien Reader Software are used to effectively estimate the level of liquid in any surface or underground tank. The experimental set up is presented and an expository presentation is made of the passive tag design, modelled and simulated and adopted for same application.

No

No / A wireless sensor network is a network of large numbers of sensor nodes, where each sensor node is a tiny device that is equipped with a processing, sensing subsystem and a communication subsystem. The critical issue in wireless sensor networks is how to gather sensed data in an energy-efficient way, so that the network lifetime can be extended. The design of protocols for such wireless sensor networks has to be energy-aware in order to extend the lifetime of the network because it is difficult to recharge sensor node batteries. We propose a protocol to form clusters, select cluster heads, select cluster senders and determine appropriate routings in order to reduce overall energy consumption and enhance the network lifetime. Our clustering protocol is called an Efficient Cluster-Based Communication Protocol (ECOMP) for Wireless Sensor Networks. In ECOMP, each sensor node consumes a small amount of transmitting energy in order to reach the neighbour sensor node in the bidirectional ring, and the cluster heads do not need to receive any sensed data from member nodes. The simulation results show that ECOMP significantly minimises energy consumption of sensor nodes and extends the network lifetime, compared with existing clustering protocol.

Au lendemain de la seconde Guerre mondiale, le multilatéralisme est devenu la condition de légitimité des interventions à des fins de protection humaine. Néanmoins le multilatéralisme suscite des problèmes de coopération, de commandement et de contrôle dans une force multinationale composée des contingents ayant des cultures militaires propres. Les échecs successifs de la première moitié de la décennie 1990 générèrent des travaux concentrés sur le maintien de la paix suivant une démarche up-down. Ils proposèrent dans un premier temps, la création d’une doctrine ‘‘robuste’’ qui comprendrait également l’élaboration des règles d’engagement (ROE) fermes et dans un second temps, la mise en oeuvre de mandats sans ambiguïtés. Or, tant que la configuration du Conseil de sécurité restera inchangée, les mandats seront toujours ambigus puisque les résolutions dont ils découlent laissent une part d’ambiguïté afin d’éviter le risque de veto. Chaque opération de paix ayant ses particularités propres, la création d’une doctrine robuste pour le maintien de la paix ne serait pas efficace. Posant les directives déterminant le niveau de force qui peut être utilisé dans diverses situations, les ROE se trouvent au coeur des opérations de paix et affectent la légitimité de celles-ci. Plutôt qu’une doctrine, la création d’un régime des ROE suivant une démarche bottom-up et son intériorisation par les casques bleus entrainerait une harmonisation de leurs comportements. Il serait alors possible de rechercher l’émergence d’une perception commune entre les Etats à l’égard du maintien de la paix et ce à travers une norme safe-efficient qui assurerait un environnement safe pour les soldats et un environnement efficient pour la réussite des opérations de maintien de la paix. Plus les Etats seront conscients des problèmes et des ambiguïtés relatifs aux opérations de paix, plus ils pourront avoir la volonté politique de mettre en oeuvre des mandats plus crédibles par l’intermédiaire de cette norme safe-efficient. / After the Second World War, multilateralism has become the legitimacy condition of interventions for human protection. Nevertheless, multilateralism creates problems of cooperation, command and control in a multinational force, which is composed of contingents having their own military cultures. Successive failures of the first half of the 1990s generate peacekeeping studies following an up-down path. Initially, they had proposed to create a “robust” doctrine that comprehends the drafting of firm Rules of Engagements (ROE), and in later times, they proposed to carry out the mandates without ambiguities for peace operations. Yet, as long as the configuration of the Security Council remains the same, the mandates will always be ambiguous, given that they are derived from the already ambiguous resolutions avoiding the risk of veto. Since every peace operation has its own particularities, the creation of a robust peacekeeping doctrine would not be efficient. ROEs are the directives issued by competent military authority that delineate the circumstances and limitations about the use of force. They are at the core of the peace operations and influence their legitimacy. Rather than a doctrine, the creation of a regime of ROE following a bottom-up path, and its internalization by peacekeepers, lead to a harmonization of their behaviors. It will then become possible to look for the emergence of a common perception between states about peacekeeping, and through this, a safe-efficient norm will emerge. This will secure a safe environment for soldiers and an efficient environment for the success of peacekeeping operations. The more awareness is created about problems and ambiguities concerning peace operations, the more willing will states become to carry out credible mandates through this safe-efficient norm.