基于片上DC-DC的CMOS光接收机前置放大器

利用CSMC 0.6μm CMOS工艺,设计了基于片上DC-DC转换器的光接收机前置放大器。电路采用可调跨阻放大器与片上DC-DC结构,有效地克服了单端跨阻放大器易受电源波动的干扰,并解决了高灵敏度与低失真相互矛盾的问题。模拟结果表明,输入动态范围为83 dB(峰-峰值=0.2μA~3 mA),等效输入电流噪声为1.2 pA/Hz(155 MHz),可稳定工作在155 Mb/s速率上;在5 V电源电压下,功耗为95 mW。     

Nano-size crystallites in Mo/Si multilayer optics

In this paper, we present an experimental study on the structural and crystalline properties of electron beam evaporated Mo/Si multilayers. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) experiments were used to characterize the crystalline nature of Mo and Si. TEM and XRD show that Si grows amorphous, while Mo clearly crystallizes. The Mo crystallites show no preferred growth orientations and a columnar growth mode, with crystallite sizes limited by the Mo layer thickness. From samples with low Mo content, we show that crystallization of Mo starts directly at the Mo/Si interfaces, with the formation of a Mo₃Si compound. The crystallite lattice strains that develop during Mo-on-Si growth due to lattice mismatches, will add to the macroscopic multilayer stress. By comparing Mo lattice strains derived from XRD with changes in substrate curvatures, as determined by interferometry, we show that compressive and tensile substrate deformations are predominantly caused by the internal crystallite strains.     

Study of the effect of ultrasonic treatment on the surface composition and the flotation performance of high-sulfur coal

This paper highlighted the use of X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectroscopy to investigate the changes on the surface composition of high-sulfur coal and pyrite before and after ultrasonic conditioning. The results showed that ultrasonic conditioning resulted in a decrease in the contents of iron and sulfur in coal, an increase in the content of element carbon, and an increase in the purity of the coal. Conversely, ultrasonic conditioning led to an increase in the content of iron and sulfur in pyrite, a decrease in the impure content of calcium, and a relative increase in the purity of the pyrite after ultrasonic conditioning. This study verified that on the one hand, ultrasonic conditioning can promote the pyrite separation from the high-sulfur coal, with the separated pyrite taking the form of FeS; on the other hand, it can produce a cleaning effect on the surface of coal and pyrite with the consequent increase both in hydrophobicity of coal and hydrophilicity of pyrite. The paper introduced ultrasonic pre-treatment of the slurry and stepped froth removal tests of high-sulfur coal and the study on the yield, ash and sulfur content of clean coal in different phases. The results gave further evidence of the increases both in the rate and the selectivity of flotation. This study shows that ultrasonic conditioning can enhance the performance of de-sulphurization of high-sulfur coal flotation.     

Facile synthesis of ordered nanocrystalline alumina thin films with tunable mesopore structures

Mesoporous alumina layers have attracted attention for their potential use in ultrafiltration of salts, as a heterogeneous catalyst support, an adsorbent in environmental cleanup, and in petroleum refinement. The ability to control the fast hydrolysis rate of the inorganic precursors using simple and inexpensive routes is important for that potential to be realized. Herein, we introduce a novel and facile route to synthesize mesoporous alumina thin films from the combination of inexpensive and commercially available copolymer with aluminum chloride or nitrate (salts) in an EtOH–surfactant–NH₃ · H₂O–salts (EsNs) system through the evaporation-induced self-assembly (EISA) method. Mesoporous alumina layers obtained utilizing the EsNs system have ordered and tunable pore structures. The ability to easily control the mesophases of the alumina layers within a short time provides distinct advantages over previously reported synthesis procedures. Most importantly, we demonstrate that the binding of surfactant and NH₃ · H₂O for the formation of hydrogen bond between them in the EsNs system controls the fast hydrolysis rate of the inorganic species. This allows for the synthesis of nanocrystalline alumina layers via the aluminum oxo-clusters’ assembly with the surfactant. Such simple route may be applied in the synthesis of other non-silica mesostructured oxides.     

Distributed multi-join query processing in data grids

Query processing in data grids is a difficult issue due to the heterogeneous, unpredictable and volatile behaviors of the grid resources. Applying join operations on remote relations in data grids is a unique and interesting problem. However, to the best of our knowledge, little is done to date on multi-join query processing in data grids. An approach for processing multi-join queries is proposed in this paper. Firstly, a relation-reduction algorithm for reducing the sizes of operand relations is presented in order to minimize data transmission cost among grid nodes. Then, a method for scheduling computer nodes in data grids is devised to parallel process multi-join queries. Thirdly, an innovative method is developed to efficiently execute join operations in a pipeline fashion. Finally, a complete algorithm for processing multi-join queries is given. Analytical and experimental results show the effectiveness and efficiency of the proposed approach.     

分户采暖系统技术分析

从室内采暖系统常见的问题入手,提出解决这些问题的关键在于应用分户采暖系统并进行热量计量。     

Convergence of self-tuning Riccati equation with correlated noises

For the linear discrete time-invariant stochastic system with correlated noises,and with unknown model parameters and noise statistics,substituting the online consistent estimators of the model paramet...     

State feedback stabilization of discrete linear switching systems subject to nonsymmetrical state and control bounds

Stabilization problem of discrete-time linear switching systems with bounds on the state and control input is solved in this paper.First,the synthesis of state feedback controllers that ensure the stab...