Future wireless communication systems will have higher data transmission rates and energy efficiencies than those used today. This fact raises serious challenges to the design of conventional transceiver architectures. This doctoral research develops energy-efficient RF transmitters and receivers for next-generation wireless communications. It begins with a theoretical analysis of the injection locking of oscillators and a modified Class-E power amplifier (PA) for use in developing the proposed transmitter and receiver. Based on the presented theory, a novel envelope elimination and restoration (EER)/polar transmitter using injection-locked oscillators (ILOs) and a novel cognitive polar receiver using two ILO stages are proposed. The EER/polar transmitter combines the approaches of EER/polar modulation and injection locking to achieve linear amplification with a high gain and high efficiency. Experimental results demonstrate its effectiveness for delivering WCDMA and EDGE signals. Additionally, the cognitive polar receiver utilizes two ILO stages to extract the modulation envelope and phase components of a received nonconstant envelope modulation signal without using a phase-locked loop (PLL)-based carrier recovery circuit. Experiments are conducted to verify the feasibility of the novel architecture by performing £k/4 DQPSK and QPSK demodulation. Rigorous theoretical analysis and experimental verification prove that both the proposed transmitter and the receiver are effective for energy-efficient wireless communications.

This thesis improved the structure of traditional envelope elimination and restoration transmitter by replacing the analog components of envelope detector and limiter using digital processing technique of polar transformation. Envelope signal was modulated by delta-sigma modulation, which could suppress the quantization noise and would be good for integrated circuit design. The front end analog circuits of transmitter used high efficiency class-S and class-E power amplifiers to amplify envelope and phase signal separately and finally combined them at the output of class-E power amplifier. The RF transmitters using polar modulation had advantages of high efficiency and linearity when transmitting high PAPR-valued digital modulation signals. For example, when transmitting the QPSK-modulated signal with 900MHz carrier and 1Msps data rate, the transmitter was measured with efficiency as high as 60%, ACPR above 34dB, and EVM less than 6.5%.

As the international relations changed tremendously after the Cold War Era, the foreign policies of Mainland China also made a great deal change. And due to the collapse of the Soviet Union, Mainland China came to new perspectives on international systems; that is, the ¡§multi-polar international system¡¨ had replaced the ¡§bipolar system.¡¨ And under the hegemony of the United States, the international system should transform into ¡§one superpower with multi-polar system.¡¨ But whatever the international system could be, Mainland China has begun to consider itself as a pole in the international system after the Cold War. The concept of being a pole became more evident when Ze-Min Jiang unveiled the idea of ¡§major power foreign policy¡¨ in 1997. This is became the concept of ¡§major power¡¨ was somewhat similar with the ¡§pole¡¨ as Xiao-Ping Deng proposed before. Under the premise of being an international major power, ¡§power¡¨ had been set up as the diplomatic goal that Mainland China kept pursuing. In other words, Mainland China wanted to be an internationally powerful and influential ¡§major power.¡¨ And the importance of the Third World countries served the place where China expected them to be strategic partners. However, as the confrontation of the United States and the Soviet Union gradually vanished, the political ideology that maintained the relationship between Mainland China and the Third World also weakened. Having kept the mission of making good relations with the Third World countries, the Chinese found it was necessary to have common interest for both, and therefore, even economic strategy as well as economic measures could play alternative role for Chinese foreign policy.

Abstract¡G This thesis mainly implemented an RF transmitter with high efficiency and high linearity. A Cartesian to Polar transformation was implemented by CORDIC algorithm using FPGA. By replacing the envelope detector and limiter in traditional envelope elimination and restoration transmitter, this technique not only achieves more accurate modulation quality, but also becomes more suitable for single chip system. Applying the first order delta-sigma modulation and highly efficient switching-mode DC converter, the envelope signal was amplified highly efficiently. Due to the class-E power amplifier having good linear relation between output voltage and supply voltage, the polar modulation transmitter can achieve high efficiency and high linearity simultaneously. Furthermore, this thesis purposed a new transmitter with two-terminal time-varying modulation. The IQ modulated signal was fed to the input terminal of class-E amplifier, while the envelope signal was used to amplitude modulate the voltage supply terminal. With dynamic input power control, the conversion efficiency and linearity are independent of output power in the purposed architecture. From the experimental results, while transmitting a QPSK-modulated CDMA2000 1x signal with 1.2288 Msps data rate, the transmitter achieve 48 % in drain efficiency, 47 dB in ACPR, and 6 % in EVM at the output power ranging from 10 to 22 dBm.

After the ending of the Cold War and the break down of the Soviet Union, the old polarized system collapsed and the new international structure of world powers hasn't formed yet in a short time. Researchers of international relations have diversely defined the new framework of world power as ¡§uni-polar¡¨¡B ¡§ multi-polar¡¨ or ¡§multi-powers under uni- polar¡¨. From the perspectives of China, the definition of ¡§ multi-powers under uni- polar¡¨ can most properly describe the new international system and is completely in accordance with the international strategy of China. In the assumption, uni-polar means US and multi-powers means other important powers, including major regional actors or groups like China､Russia､Japan､EU and some newly developing powers like India､Brazil and South Africa. In response to the huge change of international system and in order to develop much more power of influence on international affairs,China introduced the concept of ¡§New Security perspective¡¨ to try to develop common interests with major powers and neighboring states through cooperation and dialogues. Then in 2003, China publicly proposed the concept of ¡§Peaceful Rise¡¨ and soon has been regarded as competitive opponent by U.S.A and countries around China. The way China rose aroused the attention of the international society and ¡§China Threat Theory¡¨ has become more and more well-known. The purpose of this research is to explore the theoretical basis､strategic value and purposes of the theory about China's peaceful rise, and extensively to analyze how China develops new international strategies and comprehensive national power. Additionally, I try to develop findings about the theme and hope that will helpful for our government to scheme corresponding policies to ensure our national security.

ABSTRACT In this paper we describe the use of electrospray-assisted pyrolysis ionization/mass spectrometry (ESA-Py/MS) to selectively ionize trace polar compounds that coexist with large amounts of nonpolar hydrocarbons in synthetic polymer, crude oil, amber, humic substances, and rubber. Samples of different origins are distinguished rapidly by their ESA-Py mass spectra without prior separation or chemical pretreatment. During ESA-Py analysis, the samples in their solid or liquid states were pyrolyzed at 590 ¢XC using a commercial Curie-point pyrolytical probe; the gaseous pyrolysates were transferred into a glass reaction cell; the polar compounds (M) in the pyrolysates were then ionized in the form of protonated molecules (MH+), through their reactions with the charged species in the ESI plum. Although the major components of the pyrolysates are nonpolar hydrocarbons, their lack of functional groups that can receive a proton in the ESA-Py source results in no hydrocarbon ion signals being produced; thus, the ions detected in ESA-Py mass spectra all result from trace polar component in the pyrolysates.

Liquid dispersions of colloidal particles play a big role in nature and as industrial products or intermediates. Their material properties are largely determined by the liquid-mediated particle-particle interaction. In water-based systems, electric charge is ubiquitous and electrostatic particle interaction often is the primary factor in stabilizing dispersions against decomposition by aggregation and sedimentation. Very nonpolar liquids, by contrast, are usually considered free of charge, because their low dielectric constant raises the electrostatic cost of separating opposite charges above the available thermal energy. Defying this conventional wisdom, nonpolar solutions of certain ionic surfactants do support mobile ions and surface charges. Even some nonionic surfactants have recently been found to raise the conductivity of nonpolar oils and promote surface charging of suspended particles, but this counter-intuitive behavior is not yet widely acknowledged, nor is the mechanism of charging understood. The present study provides the first characterization of the electrostatic particle interaction caused by nonionizable surfactants in nonpolar oils. The methods used in this study are video microscopy experiments where particle positions of equilibrium ensembles are obtained and translated into particle interactions. Experimentally, equilibrium particle positions are monitored by digital video microscopy, and subjected to liquid structure analysis in order to find the energy of interaction between two particles. The observed interaction energy profiles agree well with a screened-Coulomb potential, thus confirming the presence of both surface charge and mobile ions in solution. In contrast to recently reported electrostatic particle interactions induced by ionic surfactants in nonpolar solution, the present study finds evidence of charge screening both above and below the surfactant's critical micelle concentration, CMC. Fitted Debye screening lengths are much larger than in aqueous systems, but similar to the Debye length in nonpolar oils reported for micellar solutions of ionic surfactants cite{hsu_charge_2005}. Radial distribution functions obtained from experiments are compared to Monte-Carlo simulations with input potentials obtained from a fit to the interaction measurement. The measured electrostatic forces and fitted surface potentials are fairly substantial and easily capable of stabilizing colloidal dispersions. Although few in number, surface charges formed on polymer particle surfaces submerged in nonpolar solutions of nonionizable surfactants create surface potentials comparable to those in aqueous systems.

No description available.

Two highly polar sol-gel coatings were developed for capillary microextraction (CME). One of the coatings contained cyanopropyl-polydimethylsiloxane (CN-PDMS) and the other low molecular weight polyethylene glycol. These highly polar coatings were immobilized via sol-gel chemistry allowing for direct chemical bonding to the inner surface of fused silica capillaries. These sol-gel coated microextraction capillaries were employed in CME for solvent-free microextraction and preconcentration of trace analytes (polar, moderately polar, and nonpolar) from aqueous matrices. CN-PDMS and short chain PEG extraction phases exhibit both polar and polarizable characteristics. Therefore, both sol-gel CN-PDMS and short chain sol-gel PEG coatings were able to extract analytes of different polarity from aqueous media. Both sol-gel CN-PDMS and sol-gel PEG coatings provided effective extraction of polar analytes such as free fatty acids, alcohols, and phenols without requiring derivatization, pH adjustment or salting out procedures commonly used in SPME experiments with conventional coatings. For each of these coatings, detection limits on the order of nanogram/liter (ng/L) were achieved for both polar and nonpolar analytes extracted simultaneously from aqueous media followed by GC-FID analysis. Both sol-gel CN-PDMS and short chain sol-gel PEG coated microextraction capillaries showed excellent run-to-run and capillary-to-capillary extraction reproducibility (GC peak area RSD < 6% & 5%, respectively) for nonpolar as well as polar analytes. For the sol-gel CN-PDMS coatings, the upper allowable conditioning temperatures were 330 degrees C and 350 degrees C, for the extraction of polar and nonpolar organic analytes, respectively. Similarly, the sol-gel PEG coatings used for the extraction of polar organic analytes survived a conditioning temperature of 340 degrees C. Both sol-gel CN-PDMS and sol-gel PEG coated microextraction capillaries showed no significant changes in the peak areas of the extracted analytes even after being washed with organic solvents (dichloromethane and methanol (1:1), v/v) for 24 hours. The excellent thermal and solvent stabilities can be attributed to the presence of chemical bonds between the sol-gel coatings and the fused silica surface.

The Arctic—warming at twice the rate of the rest of the planet—is a source of striking imagery of amplified environmental change in our time, and has come to serve as a spatial setting for climate crisis discourse. The recent alterations in the Arctic environment have also been perceived by some observers as an opportunity to expand economic exploitation. Heightened geopolitical interest in the region and its resources, contradicted by calls for the protection of fragile Far North ecosystems, has rendered the Arctic an arena for negotiating human interactions with nature, and for reflecting upon the planetary risks and possibilities associated with the advent and expansion of the Anthropocene—the proposed new epoch in Earth history in which humankind is said to have gained geological agency and become the dominant force over the Earth system. With the Arctic serving as a nexus of crosscutting analytical themes spanning contemporary history (the late twentieth and the early twenty-first century until 2015), this dissertation examines defining characteristics of the Anthropocene and how the concept, which emerged from the Earth system science community, impacts ideas and assumptions in historiography, social sciences and the environmental humanities, including the fields of environmental history, crisis management and security studies, political geography, and science and technology studies (STS). The primary areas of empirical analysis and theoretical investigation encompass constructivist perspectives and temporal conceptions of environmental and climate crisis; the role of science and expertise in performing politics and shaping social discourse; the geopolitical significance of telecoupling—a concept that reflects the interconnectedness of the Anthropocene and supports stakeholder claims across wide spatial scales; and implications of the recent transformation in humankind’s long duration relationship with the natural world. Several dissertation themes were observed in practice at the international science community of Ny-Ålesund on Svalbard, where global change is made visible through a concentration of scientific activity. Ny-Ålesund is furthermore a place of geopolitics, where extra-regional states attempt to enhance their legitimacy as Arctic stakeholders through the performance of scientific research undertakings, participation in governance institutions, and by establishing a physical presence in the Far North. This dissertation concludes that this small and remote community represents an Anthropocene node of global environmental change, Earth system science, emergent global governance, geopolitics, and stakeholder construction in an increasingly telecoupled world. / <p>QC 20151211</p>