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Catalytic dry (CO2) reforming of plastic-derived syngas is a promising method of producing hydrogen-rich syngas and reducing greenhouse gases. The development of catalysts with high activity and stability is critical for this reaction. In this study, we fabricated core-shell structured Ni@Al2O3 catalysts with different shell thicknesses using advanced polyol and sol-gel methods. The effects of different Al/Ni ratios on the activity and stability of the catalysts in the CO2 reforming reaction were investigated. The main challenge for CO2 reforming of methane is carbon deposition. In the developed catalysts, the mesoporous Al2O3 coating outside the Ni core enhances the stability. However, the interaction between the core and the shell strongly affects the catalyst activity and product selectivity in the reaction. The catalyst with an Al/Ni ratio of 2 exhibited the highest methane conversion of up to 88% and the lowest carbon deposition, compared to the congeners with Al/Ni ratios of 1 and 3.

Aluminum species in AlCl₃–arene and AlCl₃–CuCl–arene solutions (including benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene) were investigated using ²⁷Al NMR and infrared (IR) spectroscopy. The AlCl₃·arene and Al₂Cl₆·arene complexes were demonstrated experimentally. AlCl₃ could not coordinate with benzene and toluene at a low temperature (40 °C) but could form complexes at a high temperature (80 °C). AlCl₃ could coordinate with xylene and mesitylene to form Al₂Cl₆·arene complexes at both low and high temperatures (40 and 80 °C). As for AlCl₃–CuCl–arene solutions with a molar ratio of 1:1:2, two signals were observed in ²⁷Al NMR spectra. The signal at around 101 ppm was assigned to CuAlCl₄·2arene complexes, and the other signal at around 96 ppm belonged to AlCl₃·arene complexes. The characteristic peaks of AlCl₃–CuCl–arene solutions in IR spectra moved toward the low field due to the strong π-back-bonding. The CuAlCl₄·2arene complexes would convert to CuAl₂Cl₇·2arene complexes with a further increase in AlCl₃ content when the molar ratio of AlCl₃/CuCl exceeded 1. The synthesis mechanism of AlCl₃–CuCl–arene solutions was analyzed by in situ Fourier transform IR (FTIR) spectroscopy. Three reaction pathways originating from different aluminum species were proposed.

This study aims to develop a two-stage fluidized catalytic bed reactor system for continuous co-production of carbon nanotubes (CNTs) and hydrogen from waste plastics gasification. Ni/Al-SBA-15 and Ni–Cu/CaO–SiO2 catalysts have been synthesized and granulated for CNTs synthesis and hydrogen production in the first- and second-stage reactor, respectively. The operating parameters, including reaction temperature and equivalence ratio (ER), were investigated to confirm the feasibility for CNTs and hydrogen production of this system. The Ni/Al-SBA-15 added in the first-stage reactor enhanced the waste plastics degradation to produce CH4 and C2–C5 hydrocarbons with increasing temperature, which could be used as the source for CNTs synthesis. Lowering the ER promoted the catalytic thermal cracking and reforming of hydrocarbons that contributed to the CNTs and hydrogen production. Nevertheless, the H2 production rate showed a significant increase to 857.6 mmol/h-g catalyst with the assistance of Ni–Cu/CaO–SiO2 in the second-stage reactor. The produced smaller-molecule hydrocarbons from the second-stage reactor with higher temperatures could benefit the co-production of CNTs and hydrogen. The two-stage fluidized catalytic bed gasification system exhibited an optimal performance of high fraction CNTs and H2 when temperatures of first- and second-stage reactor were controlled at 600 and 800 °C, respectively, with 0.1 ER.

In this study, a core–shell structured catalyst composed of a nickel core coated with a high thermal-stability shell layer was prepared for the decomposition of waste plastics to produce hydrogen. Ceria–zirconia mixed metal oxide was used as the coating layer to protect the active phase of the catalyst. The as-prepared catalyst was firstly tested using a methane cracking process to evaluate its stability under high temperature and coking conditions. The special redox characteristics of the Ni@CeO2–ZrO2 core–shell-structured catalyst provide lattice oxygen to oxidize carbon produced during the reaction and extend the life of the catalyst during the coking resistance test. Different pore sizes in the functional shell were prepared by adding a templating agent, and the catalyst was tested for its ability to produce hydrogen from plastic waste. The CeO2–ZrO2 shell promoted the production of active oxygen species and enhanced the dispersion of the Ni cores, which are beneficial attributes for plastic waste decomposition.

In the present work, a core-shell structured Co/SiO2@HZSM-5 catalyst was prepared for hydrogen production from syngas of plastic waste gasification. The cobalt catalyst was coated with HZSM-5 shell through a hydrothermal process, and the Co/SiO2@HZSM-5, with different loadings of HZSM-5 (e.g., 10–30 wt %) exhibited excellent activity and durability for dehydrogenation reactions. The amount of HZSM-5 was found to be an important factor for hydrogen production. Temperature-programmed reduction with H2 and temperature-programmed desorption of ammonia was applied to determine the active site and the acidity of prepared catalyst, respectively. The prepared Co/SiO2@HZSM-5 was tested through reforming of plastic gasification syngas and shown superior hydrogen production ability (∼90%) and stability (over 15 h). The effects of reduction-oxidation behavior on the catalytic performance were also discussed.

Rationale: Excessive Ang II (angiotensin II) levels lead to a profibrotic and hypertrophic milieu that produces deleterious remodeling and dysfunction in hypertension-associated heart failure. Agents that disrupt Ang II–induced cardiac dysfunction may have clinical utility in the treatment of hypertension-associated heart failure. Objective: We have examined the potential effect of celastrol—a bioactive compound derived from the Celastraceae family—on Ang II–induced cardiac dysfunction. Methods and Results: In rat primary cardiomyocytes and H9C2 (rat cardiomyocyte-like H9C2) cells, celastrol attenuates Ang II–induced cellular hypertrophy and fibrotic responses. Proteome microarrays, surface plasmon resonance, competitive binding assays, and molecular simulation were used to identify the molecular target of celastrol. Our data showed that celastrol directly binds to and inhibits STAT (signal transducer and activator of transcription)-3 phosphorylation and nuclear translocation. Functional tests demonstrated that the protection of celastrol is afforded through targeting STAT3. Overexpression of STAT3 dampens the effect of celastrol by partially rescuing STAT3 activity. Finally, we investigated the in vivo effect of celastrol treatment in mice challenged with Ang II and in the transverse aortic constriction model. We show that celastrol administration protected heart function in Ang II–challenged and transverse aortic constriction–challenged mice by inhibiting cardiac fibrosis and hypertrophy. Conclusions: Our studies show that celastrol inhibits Ang II–induced cardiac dysfunction by inhibiting STAT3 activity.

This thesis contains the formulation of theoretical models and the results of experimental studies for the problems of radiated emissions from outdoor and indoor Power Line Communication (PLC) systems in the frequency range of 1-30 MHz. DOCTOR OF PHILOSOPHY (EEE)

Ni/SiO2 core–shell catalysts were prepared by deposition–precipitation method and used to produce hydrogen from waste plastics-derived syngas. The SiO2 core synthesized by the Stober process was used as the support. This core was synthesized using various solvents, and the effect of these solvents on the morphologies and catalytic performance of the Ni/SiO2 core–shell catalysts was investigated. The synthesis parameters of the Ni/SiO2 catalysts were further investigated to enhance the metal–support interaction and dispersion of Ni on the SiO2 support. The highest catalytic activity of 181 mmol/g-h was achieved when the Ni/SiO2 core–shell catalyst was synthesized in methanol (Ni/SiO2–M) and reacted at 800 °C at a water-addition rate of 0.75 g-H2O/h. The Ni/SiO2–M catalyst, which possessed strong metal–support interaction nickel phyllosilicates, high specific area, small particle size, and homogeneous metal dispersion, exhibited the best long-term stability.

The thermochemical treatment of waste plastics to produce H2-rich syngas is a promising technique for both waste management and the regeneration of valuable energy resources. In this paper, we report the synthesis of Ni@CeO2 core–shell catalyst with different shell thicknesses. The H2 production ability of the Ni@CeO2 core–shell catalysts was tested and compared to that of the supported Ni/CeO2 catalyst, and it was determined that the H2 yield of the Ni@CeO2 core–shell catalysts was significantly higher than that of the supported Ni/CeO2 catalyst. Owing to the hollow space between the core and shell providing a reacting space for heterogeneous catalysis, the amount of H2 obtained employing the Ni@CeO2-0.5 catalyst, which was obtained using 0.5 mmol cerium nitrate, was the highest of all analyzed Ni@CeO2 catalysts in this study. The optimal H2 production rate of 730.6 mmol/(h g was obtained at 700 °C when the equivalence ratio (ER) was 0.1.

A novel and simple synthetic approach toward core–shell Fe@Al2O3 nanocomposites were developed in this study. The as-synthesized catalyst was applied to convert the methane into carbon nanotubes. Moreover, due to the properties of the core–shell structure, the amount of surfactant can be adjusted to control the pore size of the shell and further control the diameter of the carbon nanotubes. In this study, the conversion of CH4 was up to 97% and the carbon production was 135 mgC/gcat.*h, which is much higher than traditional supported catalysts under similar reaction conditions. In addition, the carbon product quality (IG/ID) was up to 1.96. The enhanced CH4 catalytic activity for the core–shell Fe@Al2O3 catalyst originated from the combined acidic sites on the surface of the Al2O3 shell and the high carbon diffusion rate of the Fe core, which led to the high efficiency of CH4 conversion and longer lifetime of the catalyst.

We focus on a dual-functional multi-input-multi-output (MIMO) radar-communication (RadCom) system, where a single transmitter communicates with downlink cellular users and detects radar targets simultaneously. Several design criteria are considered for minimizing the downlink multi-user interference. First, we consider both the omnidirectional and directional beampattern design problems, where the closed-form globally optimal solutions are obtained. Based on these waveforms, we further consider a weighted optimization to enable a flexible trade-off between radar and communications performance and introduce a low-complexity algorithm. The computational costs of the above three designs are shown to be similar to the conventional zero-forcing (ZF) precoding. Moreover, to address the more practical constant modulus waveform design problem, we propose a branch-and-bound algorithm that obtains a globally optimal solution and derive its worst-case complexity as a function of the maximum iteration number. Finally, we assess the effectiveness of the proposed waveform design approaches by numerical results., Comment: 13 pages, 10 figures. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

High density ordered Si nanowire arrays can be fabricated from a Fe2O3 template annealed from polystyrene (PS) microsphere layers via a metal-assisted chemical etching method. The metal mesh films, containing position- and density-defined pores that determine the position and density of the remaining structures after etching, are extremely important for achieving high quality Si nanowires. By adding a structural inversion process, a Au metal mesh with arrays of high density nanopores is devised as a catalyst for metal-assisted chemical etching of silicon. The density of Si nanowires can be increased to two times that of the single-layer PS microspheres and further to three times when a double layer of PS microspheres is introduced. The two-step template method for the preparation of high-density Si nanowires shows great potential in the fields of nanofabrication and nanoelectronics.

A core-shell type catalyst was applied to convert polyethylene (PE) plastic wastes into hydrogen using a two-stage pyrolysis-catalysis reactor. The effects of catalyst: plastic ratio, reaction temperature, and the suppression of coke formation on catalytic performance were investigated. Ni-Ce bimetallic catalyst was synthesized via modified polyol method, and the silica coating with different Ni:Si molar ratio was prepared with the extension of Stober method. Different thickness of silica shell was synthesized and tested for hydrogen production from PE waste. The encapsulation of Ni-Ce core by silica shell could effectively inhibit the sintering of nanoparticles under high temperature conditions. The highest amount of hydrogen production was found when the catalyst: plastic weight ratio was 1.0, and the catalytic reaction temperature was 800 °C. The core-shell catalyst also exhibited great ability of coking resistance, showing great catalytic performance within 5 times of reuse.

Operational modal analysis (OMA) is an effective method to identify structural modal parameters from response signal under operational condition. Aiming at the evaluation of different time domain OMA methods in structural modal parameters identification, both numerical simulation and experimental investigation of cantilever beam have been applied to different methods, such as Sparse Time Domain (STD) method, Least Square Complex Exponential (LSCE) method and Eigensystem Realization Algorithm (ERA), etc. The comparison results indicated that ERA is the best one, LSCE method follows and STD method is worst.

This paper introduces the software DYNAFORM which is specially used in the numerical simulation analysis of tube forming. The key components of this powerful software and the basic operating procedures are also introduced. One example of tube bending and hydroforming is simulated using this software. Based on the analyzing result, it shows that the simulation is simply and practically.

In this paper, two-periodic wave solutions are constructed for the (2 + 1)-dimensional generalized Toda lattice equation by using Hirota bilinear method and Riemann theta function. At the same time, we analyze in details asymptotic properties of the two-periodic wave solutions and give their asymptotic relations between the periodic wave solutions and the soliton solutions.

This paper addresses the mathematical relation on a set of periods and temporal indexing constructions as well as their applications. First we introduce two concepts, i.e. the temporal connection and temporal inclusion, which are equivalence relation and preorder relation respectively. Second, by studying some basic topics such as the division of “large” equivalence classes and the overlaps of preorder relational sets, we propose a temporal data index model (TDIM) with a tree-structure consisting of a root node, equivalence class nodes and linearly ordered branch nodes. Third, we study algorithms for the temporal querying and incremental updating as well as dynamical management within the framework of TDIM. Based on a proper mathematical supporting, TDIM can be applied to researching some significant practical cases such as temporal relational and temporal XML data and so on.

This paper interests a system for the non-Newtonian flow in the whole space. [14] estimated decay of it as t tends to infinity. The aim of the paper is to investigate decay problem of it and to improve a result of [14].

Very small aperture terminal (VSAT) at Ku-band is very attractive in complex terrestrial and marine environment of military or disaster scene. The small aperture antenna characteristic of VSAT leads to strong interference to adjacent satellite systems. This situation is severely aggravated as Geostationary Satellite Orbit (GSO) becomes extremely congested. Various national and international agencies have imposed regulations on VSAT adjacent satellite interference (ASI). One regulation, called ∆T /T method, is used for accessing the necessity of ASI coordination, which is sophisticated and inconvenient to carry out. Another regulation imposed limit on off-axis effective isotropic radiated power (EIRP) of terminal, and specified the maximum allowable off-axis EIRP spectral density (OESD). This paper described and analyzed the salient features of these ASI regulations. Upon demonstration of their compatible and complementary relationships, it is shown that the simpler EIRP rule can be an alternative for the more complex ∆T/T method for ultra-small terminals (USAT). In this way, it will help reduce the complexity of the coordination determining procedure.

Context: The insulin-like growth factor (IGF) and insulin receptors' (IR) axes play important roles in both breast cancer and diabetes mellitus. Aim: We tend to explore the expression characteristics of proteins in IGF/IR axis in breast cancer with type 2 diabetes mellitus (T2DM). Settings and Design: We conducted a case-control investigation of T2DM and non-diabetes (n = 40, 1:1) in breast cancer patients. Materials and Methods: Some important molecules of IGF/IR axis were detected in breast cancer tissues by immunohistochemical staining. The multivariable analyses of the relationship of clinicopathological characters with the significant molecules were also detected. Statistical Analysis Used: The results were statistically evaluated by Statistical Package for the Social Sciences (SPSS version 17.0) software. Chi-square test and logistic regression are used. Results: Higher expression of IGF 1 receptor (IGF1R) was found in breast cancers of patients with T2DM, compared those without diabetes (P = 0.044). Negative expression of human epidermal growth factor receptor 2 (Her2) was found to be associated with higher expression of IGF1R in the breast cancers of patients with T2DM. There were no differences found in the expression of proteins of IGF-1, IGF-2, IGF-binding protein 3 (IGFBP3), IR, insulin receptor substrate (IRS)-1, IRS-2 and mammalian target of rapamycin (mTOR) between T2DM group and non-diabetes group. Conclusion: Our study found that breast cancer with T2DM had a higher expression of IGF1R, and the higher IGF1R was associated with negative Her2 expression.

Ordered Si nanowire (SiNW) arrays can be fabricated by metal-assisted chemical etching. The metal mesh films (MMFs) are extremely important for achieving a high quality of the SiNWs. We have developed a two-step chemical deposition method to obtain compact porous Ag MMFs. By the separation of the nucleation and growth stages of the metal in the two-step deposition processes, the overgrowth of the metals to form randomly aggregated irregular metal particles can be overcome. Hexagonally arranged polystyrene (PS) latex microspheres have been employed as a template for the deposition of porous Ag MMFs. The spacing of the pores in the Ag MMFs is determined by the diameter of PS microspheres, and the pore size can also be tuned by changing Ar plasma etching time. One of the main advantages of the two-step deposition method lies in that Ag MMFs can be produced with PS microspheres that are not limited to a single layer, which dramatically simplifies the tedious processes of producing a monolayered PS template. The two-step chemical deposition method shows great potential in metal-assisted chemical etching.

Research on modeling and simulation of Link-16 has attracted much attention nowadays. However as one kind of legacy system, Link-16 was not constructed based on layering principles and it is not well compatible with Global Communication Grid (GCG), also known as Global Grid (GG) that has been developed with military requirement in mind. This paper concentrates on applying Global Information Grid (GIG) layering principles on modeling and simulation of Link-16 data link. The following paper is divided into two approaches, the first issue is considered in a general way for briefing GIG layering principles and secondly we analyze the Link-16 system in layering principles to see if this tactical information distribution system can be divided into distinct sub layers.

In contrast with Phase-Locked Loop (PLL), Frequency Locked Loop (FLL) has better dynamic performance. There were papers dealing with noise performance of FLL. However, under the circumstance of CW input, there were large gap between simulation results and theory results which were obtained from published papers. This paper analysis the reason of the gap and proposes an improved calculation method in the condition of four-quadrant arctangent and cross product discriminator. Results show that the improved calculation method fits the simulation result very well.

This paper gives the long sought network version of water-filling named as polite water-filling. Unlike in single-user MIMO channels, where no one uses general purpose optimization algorithms in place of the simple and optimal water-filling for transmitter optimization, the traditional water-filling is generally far from optimal in networks as simple as MIMO multiaccess channels (MAC) and broadcast channels (BC), where steepest ascent algorithms have been used except for the sum-rate optimization. This is changed by the polite water-filling that is optimal for all boundary points of the capacity regions of MAC and BC and for all boundary points of a set of achievable regions of a more general class of MIMO B-MAC interference networks, which is a combination of multiple interfering broadcast channels, from the transmitter point of view, and multiaccess channels, from the receiver point of view, including MAC, BC, interference channels, X networks, and most practical wireless networks as special case. It is polite because it strikes an optimal balance between reducing interference to others and maximizing a link's own rate. Employing it, the related optimizations can be vastly simplified by taking advantage of the structure of the problems. Deeply connected to the polite water-filling, the rate duality is extended to the forward and reverse links of the B-MAC networks. As a demonstration, weighted sum-rate maximization algorithms based on polite water-filling and duality with superior performance and low complexity are designed for B-MAC networks and are analyzed for Interference Tree (iTree) Networks, a sub-class of the B-MAC networks that possesses promising properties for further information theoretic study., Comment: 63 pages, 12 figures

We take two new approaches to design efficient algorithms for transmitter optimization under rate constraints to guarantee the Quality of Service in general MIMO interference networks, named B-MAC Networks, which is a combination of multiple interfering broadcast channels (BC) and multiaccess channels (MAC). Two related optimization problems, maximizing the minimum of weighted rates under a sum-power constraint and minimizing the sum-power under rate constraints, are considered. The first approach takes advantage of existing efficient algorithms for SINR problems by building a bridge between rate and SINR through the design of optimal mappings between them so that the problems can be converted to SINR constraint problems. The approach can be applied to other optimization problems as well. The second approach employs polite water-filling, which is the optimal network version of water-filling that we recently found. It replaces almost all generic optimization algorithms currently used for networks and reduces the complexity while demonstrating superior performance even in non-convex cases. Both centralized and distributed algorithms are designed and the performance is analyzed in addition to numeric examples., Comment: 43 pages, 9 figures, and 10 tables. Peking University and University of Colorado at Boulder Joint Technical Report, June 28th, 2010

We take two new approaches to design efficient algorithms for transmitter optimization under rate constraints, to guarantee the Quality of Service in general MIMO interference networks, which is a combination of multiple interfering broadcast channels (BC) and multiaccess channels (MAC) and is named B-MAC Networks. Two related optimization problems, maximizing the minimum of weighted rates under a sum-power constraint and minimizing the sum-power under rate constraints, are considered. The first approach takes advantage of existing efficient algorithms for SINR problems by building a bridge between rate and SINR through the design of optimal mappings between them. The approach can be applied to other optimization problems as well. The second approach employs polite water-filling, which is the optimal network version of water-filling that we recently found. It replaces most generic optimization algorithms currently used for networks and reduces the complexity while demonstrating superior performance even in non-convex cases. Both centralized and distributed algorithms are designed and the performance is analyzed in addition to numeric examples., Comment: 30 pages, 8 figures, and 5 tables. Submitted to IEEE Transactions on Signal Processing, Jun. 2010

Al 2 O 3 thin films were characterized by optical and structural properties, as well as LIDT under 355 nm Nd:YAG laser. It was found that the deposition temperature had no clear effect on the LIDT in our experiments.

We address the problem of throughput optimization in MIMO-TDMA downlink using orthogonal random beamforming (ORBF), which has been intensively studied recently because of its ability to exploit multi-user diversity and spatial multiplexing gains with partial channel state information (CSI). We formulate an optimization problem which aims at maximizing the total throughput under the constraint of individual long term throughput guarantee for each user. Although this problem is generally non-convex, we find that the optimal solution can be found with high probability by combine convex optimization algorithms with a well designed initial algorithm. By comparing the solution of the proposed method with the optimal value of the dual problem, we showed that the optimal throughput is usually achieved by the proposed method.

On the basis of analyzing the limitations of mobile IP protocol in pervasive computing environment and in combination with the technological advantages of mobile agent, this paper introduces a mobile-agent-based application model of pervasive mobile devices. With the introduction of mobile agent into the pervasive mobile devices, the application model enables all corresponding IP messages to go through the mobile agent, which can directly detect the status information of the IP messages, thus making it possible to switch the mobile devices smoothly. Through handoff delay analysis and simulation experiments, the paper also analyses and contrasts the performance of the pervasive mobile devices before and after the mobile agent is introduced. The results show that with the introduction of mobile agent, the pervasive mobile devices can switch smoothly and swiftly, decrease handoff delay and the status information in the process of the transmission and reduce the loss ratio of handoff of the mobile devices, thus effectively improving the performance of the mobile networks in the pervasive computing environment.

In this paper, we describe and analyze a new two-step frequency estimation algorithm for pilot symbol assisted modulation (PSAM) systems with a non-uniform pilot pattern. The burst structure includes some consecutive pilots at the beginning of each burst and some sparse ones over the burst. Compared with the FFT-based (Fast Fourier Transform based) algorithm, its computational complexity is reduced greatly. It facilitates the estimation of large frequency offsets and high accuracy. Its estimation range is about plusmn20% of the symbol rate and its accuracy is close to the Cramer-Rao bound (CRB) for a low signal-to-noise ratio (SNR).

We propose an iterative data-aided algorithm based on maximum likelihood criteria for carrier frequency estimation in burst-mode phase shift keying (PSK) transmission. The proposed algorithm has a low threshold and its estimation range is large, about plusmn40% of the symbol rate. In addition, its accuracy is close to the Cramer-Rao bound (CRB) at signal-to-noise ratio (SNR) above threshold. The performance of the proposed algorithm is better and its computational complexity is also lower compared with previous ML-based algorithms.

In traditional feedback structure of direct sequence spread spectrum (DS-SS) receiver, delay lock loop is a prevailing approach to estimate the timing error. However, in burst communication, it is hard for DLL to be in transient state or lock the signal with high accuracy. In this paper, an efficient feedforward PN code timing recovery scheme is proposed for DS-SS systems. The received signal after the chip-matched filter is two times over-sampled. The characteristics of DS-SS signal are explored to make the synchronization scheme efficient and simple in such a low sampling rate. Three sets of correlation values with different timing offsets are stored to estimate the code timing and carrier phase error. With very low computational complexity, the proposed scheme can make the performance approaches to the DS- SS systems with ideal synchronization in an AWGN channel.

In this paper, we describe and analyze an efficient non-date-aided (NDA) symbol timing recovery algorithm named the Quadratic Approximation (QA) algorithm. Compared with the Tone Filtering (TF) algorithm, the algorithm presented here is low-complexity. It requires only one multiplication per burst. Its performance is better than that of the TF algorithm in terms of the estimated standard deviation and sensitivity to frequency offsets.

In this paper, an efficient iterative timing and carrier phase recovery scheme is proposed for LDPC-Coded Direct Sequence Spread Spectrum (DS-SS) systems. The received signal after the chip-matched filter is two times over sampled per chip. The characteristics of DS-SS signal and LDPC decoder are explored to make the synchronization scheme efficient and simple in such a low sampling ratio. Three sets of correlation values provided by three correlators with different timing offsets are stored to estimate timing and carrier phase. The estimation is performed once per decoding iteration based on the maximum likelihood theory aided by hard decision obtained from LDPC decoder. The overall complexity of this scheme is very low and the performance of the proposed scheme approaches that with the ideal synchronization on AWGN channel.

A simplified ML-based iterative synchronization scheme is proposed in this paper for LPDC-coded systems. Symbol timing and carrier phase are estimated in a simple way based on the maximum likelihood theory aided by hard decision obtained from LDPC decoder. The synchronized samples input to the decoder are updated when a new iterative estimation for symbol timing and carrier phase is completed. The synchronized samples are reconstructed by quadratic interpolation which is very simple and can be implemented in parallel. This approach is applied to a LDPC-coded QPSK system over AWGN channel. Simulation results demonstrate that the performance of the proposed scheme approaches that with the ideal synchronization

A distributed control system (DCS) based on two-layer networks for experimental teaching is presented in this paper. Three sets of equipments are used as process objects with their parameters such as pressure, temperature, level and flow rate being controlled variables. This system has multiform training functions. Students can not only set up basic experiments about the process control, but can also design complicated control system. The result of 4 years' use shows: it is an ideal engineering simulating system for students major in industrial automation.

In this paper, two reduced-complexity timing detectors for MC-CDMA signals based on incorporating the on-time arm in timing error signal update are proposed and analyzed. By theoretical analysis and simulations, it is shown that the simplified approaches provide superior performance for low Eb/N0 with respect to the classical non-coherent early-late gate detector.

A novel timing tracking algorithm suited for multi-carrier DS-CDMA signals by introducing vector rotation and samples selecting is proposed and studied. Numerical results shows that the new scheme has a remarkable hardware simplicity advantages but no performance degradation when compared to the conventional non-coherent delayed-lock loop (DLL).

ZnO/CdS/ZnS and ZnO/ZnS/CdS nanorod array photoelectrodes were constructed and fabricated by an alternative chemical bath deposition of CdS and ZnS layers onto the surface of the ZnO nanorod array. The photoelectrochemical performances of composite photoelectrodes were investigated, and the action mechanism of ZnS buffer layers was also considered. The results show that the ZnO/ZnS/CdS nanorod array photoelectrode possesses enhanced hydrogen production efficiency. The enhancement may be attributed to the ZnS buffer layers, which are advantageous in the separation and transportation of photogenerated electron–hole pairs in ZnO/ZnS/CdS nanorod array photoelectrodes.

The stability issues of CdSe quantum dot-sensitized solar cells have been investigated in this work. Stability is one of the most relevant issues for the real-world applications of quantum dot-sensitized solar cells. We find that CdSe quantum dots deposited in air are prone to oxidation, and when the solar cells are left in air for several months, CdSe quantum dots decompose partially to form Se particles and nanoribbons. The surface oxidation and the decomposition of CdSe quantum dots worsen all the parameters of the solar cells. Electrochemical impedance characterization provides unambiguous evidence for the evolution of the cells in the ageing process, which accounts for the observed performance worsening phenomena. Preparation under an inert atmosphere suppresses to some extent the degradation of the cells. These findings have significant implications for designing viable, high-performance quantum dot-sensitized solar cells.