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Affected by the access of the DC system, when the AC line fault on the inverter side causes the commutation failure of the DC system, the AC side has the characteristics of frequency offset and high low frequency content. In the traditional protection scheme, the pilot protection is the main protection, and the distance protection is the backup protection. They are all based on the protection of the power frequency, and there are unstable operations. From the perspective of time domain, combined with the method of parameter identification, a time-domain pilot protection scheme suitable for AC/DC hybrid system is proposed, which solves the problems caused by frequency offset in principle and a protection criteria is provided; When a line fault occurs in the AC transmission line of the hybrid system, the proposed time-domain distance protection scheme all adopts the time-domain full amount of fault information, and is also solves the problems caused by frequency offset. The simulation results show that the time-domain pilot protection and time-domain distance in the protection scheme can accurately and quickly identify faults, effectively solving the problem of unstable protection action when commutation failure occurs.

The objective of this work was to investigate the effect of boletus polysaccharide (BPS) on diabetic hepatopathy in streptozotocin (STZ)–induced type 2 diabetes mellitus (T2DM) rats for the first time. The rats were fed with high-fat diet (HFD) for 4 weeks and induced with STZ by a single intraperitoneal injection to develop T2DM model. The HFD was given continually for another 4 weeks after diabetes induction, following the drugs of BPS (400 mg/kg bw/day) infused to stomach of rats once a day. After the administration, blood was drawn from the posterior orbital venous plexus of the inner canthus and the rats were then sacrificed. The blood glucose and lipid, alanine transaminase (ALT) and aspartate transaminase (AST) were detected immediately. Besides, their livers were dissected for biochemical and histopathological assays. And the levels of malonaldehyde, glutathione and antioxidant enzymes in liver were detected. In addition, histopathological examinations of liver were performed to verify the liver injury. The expressions of NF-κB, TNF-α, SREBP1c, and CYP7A1 were test to trace out the mechanistic pathways. Compared with T2DM model group, the blood glucose, TC, TG, ALT, AST, and MDA and so on were significantly reduced, and CAT, SOD, GSH, GPx were significantly increased in the rats treated with BPS. The histopathological examination showed the liver injury in BPS treated rats was alleviated. The expressions of SREBP1c, NF-κB and TNF-α were significantly decreased, and the expressions of CYP7A1 was significantly increased. All these experimental findings demonstrate that BPS exhibited antidiabetic effects rats possibly through its inhibition of oxidative stress and inflammation, supporting that BPS has a promising therapeutic effect in the treatment of diabetic hepatopathy in rats.

This paper proposes two anti-interference adaptive single-phase auto-reclosing (ASPAR) schemes for transmission lines with shunt reactors. This approach is based on faulty phase reactive power characteristics. Instantaneous power algorithm (IPA) is used to calculate the reactive power using voltage and current measurements at only one end of the transmission line. After fault extinction, faulty phase reactive power magnitude rapidly rises and can be divided into five frequency components, hence, magnitude and frequency components ratio are used to identify fault extinction time. Integral processes are included in IPA, for this reason, the proposed ASPAR schemes possess anti-interference capability, and it can be used on wind power outgoing lines with multiple kind of interference often. The proposed approach considers various transmission lines interferences: rapid transmit power fluctuation and external lightning strike. Influences of high frequency disturbance and wind power plants low voltage ride through (LVRT) process were also taken into account. The proposed ASPAR schemes is extensively investigated on a typical wind power outgoing line, Hami, Xinjiang, China via the simulation platform PSCAD/EMTDC 4.5.0.0. Different cases are studied considering rapid transmit power fluctuation and external lightning strike. The simulation results ensure the validity and feasibility of the proposed ASPAR schemes on transmission lines with and without much interference. Besides, the robustness of the proposed ASPAR schemes against varied fault location and transition resistance is also verified.

The rigid Troger's base microporous polymers were utilized to fabricate mixed matrix membranes with NH2-MIL-53 (Al) nanocrystals. Such N containing polymers have the ability to interact with NH2-MIL-53 (Al), therefore yielding transparent, robust, and plasticization–resistant hybrid membranes. The resulting membranes show a remarkable increase in gas permeability up to 3 times as a result of improved gas diffusivity and solubility without the selectivity loss. Much more improvements in CO2 solubility arise from the presence of CO2-adsorbing sites in Troger's base polymers and the CO2-selective adsorption properties of NH2-MIL-53 (Al), correspondingly leading to increased CO2 solubility selectivity. The gas separation performance shifts toward Robeson upper bonds upon the addition of MOFs. Particularly, the H2/CH4 separation performance overcomes the 2008 Robeson upper bond. In mixed gas feeds, the membranes display CO2 gas permeability up to 308 Barrer and CO2/N2 and CO2/CH4 mixed gas selectivities of 25.4 and 23.6 with virtually no evidence of plasticization. Much higher mixed-gas selectivity than permselectivity in these membranes are strongly correlated with the strongly adsorbing CO2 gas molecules blocking transport of large size molecules.

Highly permeable and selective membranes that exceed the conventional permeability-selectivity upper bound are attractive for energy-efficient gas separations. In the context microporous polymers have gained increasing attention owing to their high porosity and exceptional permeability. However, the moderate selectivity of microporous polymers caused by inherent broad distribution of cavities leads to a loss of valuable gas products, making them unfavorable for separating similarly sized gas mixtures. Here we report a new approach to designing polymeric molecular sieve membranes via multi-covalent-crosslinking of miscible blends of Polymer of Intrinsic Microporosity, i.e. bromomethyl (PIM-BM) and Tröger's Base (TB), enabling simultaneously high permeability and selectivity. Selective gas permeation is achieved via adjusting reaction temperature, reaction time and the oxygen concentration with occurrences of polymer chain scissor, rearrangement and thermal oxidative crosslinking reaction simultaneously. Upon a thermal treatment at 300 oC for 5h, membranes exhibit an O2/N2, CO2/CH4 and H2/CH4 selectivity as high as 11.1, 155.7 and 814.1, respectively, with an O2, H2 and CO2 permeability of 18.2, 358.2 and 67.6 Barrer, respectively, transcending the state-of-art upper bounds. The design strategy represents a generalizable approach to creating molecular-sieving polymer membranes with enormous potentials for energy-efficient separation processes.

Mobile edge computing (MEC) is a new paradigm that has recently received a lot of attention. It extends computing power to the network edge, where tasks are not transmitted over long distances, thus reducing the risk of sensitive information leakage and theft. By offloading tasks to MEC servers, user equipments (UEs) can not only address its own lack of computing resources, but also reduce time and energy consumption. However, compared to the increasing computing requirements of UEs, the limited resources and heavy burden of MEC servers are becoming more and more obvious. Therefore, it will be a great challenge to design a proper computation offloading scheme to meet the requirements of UEs in resource-constrained MEC. In this paper, we analyze main computation offloading schemes. We divide computation offloading scenarios into two types. One is a single-server scenario, the other is a collaborative scenario with cloud, edge server, vehicle, etc. Challenges and conclusions have also been suggested in this paper.

The structural engineering and design of 6FDA/BPDA-based copolyimide membranes at a molecular level are developed to achieve advanced membrane materials with improved CO2 plasticization resistance as well as high gas separation performance. The commercially available diamine monomers with/without various electronegative groups (-CH3, –CF3 and -Cl) have been employed to prepare 6FDA/BPDA-based copolyimides via the one-step method. All of the copolyimides show excellent solubility in the common solvent, film-forming ability and thus mechanical properties. More interestingly, the intermolecular charge transfer complex (CTC) effects is finely tuned as confirmed by the fluorescence emission spectrum. The introducing of polar chloride groups in the copolyimides could significantly strengthen the CTC effects to prevent the intrusion of condensable CO2 and limit polymeric chain movements. Thus, the membrane based on the 2,2′,5,5′-tetrachlorobenzidine (e.g. 6FDA:BPDA-TSN:TCDB (1:1:1:1)) shows the best carbon dioxide (CO2) plasticization resistance and slowest physical aging without sacrificing gas separation performance versus the membrane having weak polar groups. The CO2 plasticization pressure as high as 350 psi has been observed for the 6FDA:BPDA-TSN:TCDB membrane with polar chloride groups. This value is much higher than that of the copolyimide membranes with –CH3 or –CF3 groups ranging from 100 psi to 200 psi. Moreover, this membrane shows a good gas separation performance, e.g. CO2 permeability of 45.7 barrer and CO2/CH4 ideal selectivity of 35.2 surpassing the commercial cellulose acetate and Matrimid. Such structurally defined polymer with good mechanical strength, plasticization resistance and solubility harnesses the full potential of promising gas separation membrane materials for hollow fiber spinning. This work offers structural engineering guidance for the preparation of high-performance polymers with good tolerance to CO2-induced plasticization.

Vehicular Edge Computing (VEC) is a promising new paradigm that has received a lot of attention recently. Computation Offloading (CO) can migrate computing tasks to the network edge of VEC, which is critical for mobile applications that are sensitive to computation power. However, the dynamicity and randomness of Internet of Vehicles (IoV) lead to new features and challenges in vehicular computation offloading. Therefore, we focus on the CO in VEC. This paper depicts a broad methodical literature analysis of CO scheme and CO methods in VEC domains and divides the current works of CO into various categories. The methodical analysis of this research will help researchers to find the important characteristics of CO and select the most appropriate algorithm for computing tasks. Challenges and research directions have also been suggested in this paper.

Ionomer chain and solvent molecule interactions during solution-casting, solvent evaporation, and solidification impacts chain entanglements, spatial arrangement of functional groups, microstructure development, morphology, and physical properties. These concepts were investigated using poly(t-butylstyrene-b-ethylene-alt-propylene-b-sulfonatedstyrene-b-ethylene-alt-propylene-b-t-butylstyrene) with a fixed ion-exchange capacity of 1.0, and estimated solubility parameter of 21.8 (J/cm3)1/2. Films were solution-cast using an equal volume cyclohexane:heptane mixture (C:H), chloroform (CHCl3), and tetrahydrofuran (THF). Subsequent film structures were evaluated using transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), FT-IR, and electrochemical impedance spectroscopy. A commercially supplied film had sulfonated domains randomly distributed throughout it, and its initial proton conductivity was 11.8 mS/cm. A film created by solution-casting from C:H had a morphology containing randomly distributed sulfonated domains. This random morphology became more ordered with a lamella-like morphology when solution-cast using THF. The film produced from CHCl3 had a morphology that was between random and ordered. Film morphology differences were attributed to a poorer solvent system that inhibited chain solvation. The solution-cast film’s proton conductivity was 1.0 mS/cm for a random morphology, and 15.3 mS/cm with a lamella-like structure. Increasing the ionomer-THF solution-casting temperature to 40 °C produced a film with a 103% increase in conductivity (31.2 mS/cm). This led to a water uptake change from 29 wt% to 80 wt%. Cycling a THF solution-cast film from its dry to a wet state revealed that a lamella-like morphology would maintain its conductivity, but the commercial film’s conductivity decreased from 11.8 mS/cm to 0.98 mS/cm. Ionomer film properties were found to be dependent upon solvent quality and processing.

Manufacturing defect-free mixed matrix membranes (MMMs) especially with high nanoparticle concentrations exceeding 40 wt% is still an ongoing challenge. Desired performance improvements are often unfulfilled in MMMs with high filler loading because nanoparticles with increasing contents are prone to aggregating, forming non-selective cavities, and deteriorating membrane's mechanical properties. To address this key issue, our work develops MMMs using Troger base (TB) polymer with more hydrogen bond acceptors, polydopamine (PDA), and ZIF-8 fillers. The PDA modified ZIF-8 to create TB/ZIF-8 MMMs especially with high ZIF-8 loading over 40 wt% improves membrane mechanical properties and completely seals structural defectives to demonstrate encouraging gas selectivities. Hydrogen bonding between CN:NH and CN:OH groups within TB polymers and PDA enhances ZIF-8 interactions and reduces particle agglomeration within the polymer matrix. A TB/ZIF-8@PDA MMM containing 50 wt% ZIF-8 has H2 and CO2 permeabilities of 664.1 and 277.3 Barrer. Its ideal H2/CH4 and CO2/CH4 selectivities are 37.7 and 15.5, respectively. Equal molar CO2/CH4 mixed gas tests at various pressures demonstrate strong CO2 plasticization resistance and enhanced CO2/CH4 gas selectivity over ideal selectivity within the membranes. The combination of PDA modification technique on filler surfaces and a polymer with many hydrogen bonds acceptors is not only a feasible route to fabricate high filler loading MMMs with sealed defective structures, but also demonstrates positive impacts on membrane mechanical properties.

The CO2-induced plasticization effects impose detrimental effects on polymeric membranes separation performance. To address this issue, a high-performance crosslinked brominated 6FDA-based polyimide (BMPI) is developed in this work, exhibiting highly suppressed plasticizing effects. The permeability and selectivity of polyimide precursor membranes are tuned by introducing bromine atoms into the polyimide structure, creating a best performing membrane with bromination degree of 60%. The membrane CO2 permeability reaches 395 Barrer, and the selectivity of CO2/CH4 increases from 22.0 for a non-brominated analogue to 26.0. The debromination induced crosslinked BMPI membranes are achieved upon thermal treatment within the temperature range of 150 °C–350 °C with varied crosslinking degree, resulting in large differences for the membrane separation performance. The completely crosslinked BMPI treated at 350 °C for 10 h demonstrates high CO2 permeability of 483.6 Barrer and the CO2/CH4 selectivity of 26.0. Most importantly, the crosslinking reaction greatly stabilizes the membrane performance against plasticization under high CO2 feed pressure. Compared with the non-crosslinked membranes with a plasticizing pressure of 150 psia, the plasticization for the crosslinked membrane occurs at high CO2 pressure of 600 psia. This study provides a facile approach for the preparation of high-performance gas separation polymeric membranes with enhanced plasticization resistance.

To coordinate the protection of PMSG (permanent magnet synchronous generator), collector circuits and outgoing lines, a comprehensive and improved protection method of PMSG based wind farms with LVRT (low voltage ride through) capability is proposed. The proposed method includes adding a short time delay to the collector network current protection zone I and a directional protective relaying to the collector network protection, installing grounding transformers and zero sequence current protection, and generator low-voltage protection action improvement. A LVRT scheme consisting of variable resistance dumping circuit, grid side dynamic reactive power control and reactive power compensation control is proposed. The fault characteristics of PMSG based wind farms are analyzed, and a PMSG based wind farm in Dabancheng, Xinjiang, is used as an example to analyze typical wind farm protection configuration, the setting values considering LVRT requirements, and the coordination problems. Finally, an improved wind farm protection coordination methodology is proposed and its validity is verified by simulation.

Transferrin receptors (TfRs) are overexpressed in tumor cells but are scarce in normal tissues, which makes TfR an attractive target for drug treatment of cancer. The objective of this study was to evaluate the potential of BP9a (CAHLHNRS) as a peptide vector for constructing TfR targeted peptide-drug conjugates and selective drug delivery. Doxorubicin (DOX) was connected to BP9a via a disulfide-intercalating linker to afford a reduction-responsive BP9a-SS-DOX conjugate. By using HepG2 human liver cancer cells and L-O2 normal hepatic cells as TfR over-expressing and low-expressing in vitro models, respectively, TfR mediated cellular uptake of this conjugate was studied by using flow cytometry and confocal laser scanning microscopy. The in vitro cytotoxicities of the conjugate against HepG2 and L-O2 cells were examined by cell counting kit-8 (CCK-8) assay to evaluate its tumorous specificity. Cellular uptake and TfR blockage test results showed that the BP9a-SS-DOX conjugate gained entry into HepG2 cells via endocytosis mediated by TfR and mainly accumulated in cytoplasm. The in vitro antiproliferative activity of this conjugate against HepG2 cells (IC50 6.21 ± 1.12 μM) was approximately one-sixth of that of free DOX (IC50 1.03 ± 0.13 μM). However, its cytotoxic effect on L-O2 cells was obviously reduced compared with that of free DOX. The BP9a-SS-DOX conjugate showed specific antiproliferative activity against HepG2 liver cancer cells. Our study suggests that BP9a has the potential to target chemotherapeutic agents to tumor cells over-expressing TfR and facilitate selective drug delivery.

In this study, a peptide-drug conjugate was designed and synthesized by connecting a transferrin receptor (TfR)-targeted binding peptide analog BP9a (CAHLHNRS) with doxorubicin (DOX) through N-succinimidyl-3-maleimidopropionate (SMP) as the cross-linker. Confocal laser scanning microscopy results indicated that free DOX mainly accumulated in the nuclei of both TfR overexpressed HepG2 hepatoma cells and L-O2 normal liver cells expressing low level of TfR; most of the BP9a-DOX conjugate displayed cytoplasmic location, and its cellular uptake by HepG2 cells was obviously reduced by TfR blockage test. Nevertheless, the cellular uptake of this conjugate by L-O2 cells was much less than that of free DOX. Meanwhile, the BP9a-DOX conjugate exhibited lower in vitro antiproliferative activity against HepG2 cells than free DOX, but its cytotoxic effect on L-O2 cells was decreased compared with that of free DOX. These results suggest that BP9a could be applied as a potential TfR-targeted peptide vector for selective drug delivery.

Carbon molecular sieve (CMS) membranes were fabricated using carboxylated polyimides with various 6FpDA:DABA molar ratios. The as-prepared 6FDA-6FpDA:DABA multiblock polyimide, thermally crosslinked ones, and CMS membranes were characterized for CO2/CH4 and C2H4/C2H6 separation performance. Thermally crosslinked polyimide membranes due to decarboxylation exhibited increased gas permeability over uncrosslinked ones. All CMS membranes had enhanced gas separation performance as compared to their unmodified precursor polymer. A representative CMS membranes pyrolyzed at 576 °C had CO2 and C2H4 permeability of 3573 and 244.6 Barrer with a CO2/CH4 and C2H4/C2H6 ideal selectivity of 51.5 and 4.80. A CMS membrane pyrolyzed at 800 °C had a C2H4 permeability of 10.4 Barrer and a C2H4/C2H6 ideal gas selectivity of 24.1. Increasing polyimide pyrolysis temperature improved CMS membrane gas selectivity but reduced its permeability. Zn2+ functionalized CMS membranes exhibited enhanced gas selectivity with a slight permeability reduction. The CMS membranes excellent gas separation performances surpassed Robeson's upper-bound. These materials hold great potential for industrial applications such as CO2 separation and olefin recovery.

Today, information technology has become an important factor of productivity to promote social development. It combines with all industries in the world, develops rapidly, and has a profound impact on human production and life. Aesthetic education plays a high role in China's higher education. For a long time, people have formed much understanding of the aesthetic education of engineering majors, while information technology, as a new engineering major intersecting with all industries, has more urgent, comprehensive and profound requirements for aesthetic education. As the cradle of information technology talents, how to cultivate talents leading the development of the times has become an important topic. This paper, starting from the problems faced by aesthetic education of colleges and universities and combined with the characteristics of information technology major, points out that the purpose of information technology major to carry out aesthetic education is to achieve harmony between man and nature and ensure that information technology benefits human society, aiming to let students develop aesthetic consciousness and aesthetic ability, shape perfect personality, and create beautiful things. The paper also discusses the connotation of aesthetic education of information technology major, pointing out that information technology major should realize the organic combination of aesthetic knowledge and professional accomplishment based on its training objectives, strengthen students' document writing ability, human-machine interface design ability and code design ability in line with aesthetic requirements, and cultivate talents good at communication and cooperation and meet the needs of the information age. Based on these ideas, this paper puts forward the assumption of offering the course of"Innovative Thinking and Aesthetic Cultivation".

Delay-tolerant networks (DTNs) rely on the mobility of nodes and their contacts to make up with the lack of continuous connectivity and, thus, enable message delivery from source to destination in a “store-carry-forward” fashion. Since message delivery consumes resource such as storage and power, some nodes may choose not to forward or carry others' messages while relying on others to deliver their locally generated messages. These kinds of selfish behaviors may hinder effective communications over DTNs. In this paper, the authors present an efficient incentive-compatible (IC) routing protocol (ICRP) with multiple copies for two-hop DTNs based on the algorithmic game theory. It takes both the encounter probability and transmission cost into consideration to deal with the misbehaviors of selfish nodes. Moreover, the authors employ the optimal sequential stopping rule and Vickrey–Clarke–Groves (VCG) auction as a strategy to select optimal relay nodes to ensure that nodes that honestly report their encounter probability and transmission cost can maximize their rewards. The authors attempt to find the optimal stopping time threshold adaptively based on realistic probability model and propose an algorithm to calculate the threshold. Based on this threshold, the authors propose a new method to select relay nodes for multicopy transmissions. To ensure that the selected relay nodes can receive their rewards securely, the authors develop a signature scheme based on a bilinear map to prevent the malicious nodes from tampering. Through simulations, the authors demonstrate that ICRP can effectively stimulate nodes to forward/carry messages and achieve higher packet delivery ratio with lower transmission cost.

Comparative studies of the cyclic stability of primary, secondary, and tertiary amine-grafted silica/polymer composite fiber adsorbents upon exposure to simulated flue gas are reported. A simulated dry flue gas mixture with 200 ppm NO does not cause degradation of the amine grafted fiber adsorbents and all fibers retain their CO2 capacity in the presence of NO. In contrast, upon exposure to dry flue gas in the presence of 200 ppm SO2 at 35 °C, the primary amine containing adsorbent, CA–S–APS, shows a CO2 capacity reduction of 55% over 120 cyclic adsorption–desorption runs. As the initial SO2 induced degradation occurs in this adsorbent, the amine sites first irreversibly adsorb SO2 and then begin to gradually adsorb SO2 reversibly, as evidenced from a quantitative comparison of the amount of adsorbed SO2 to the amount of desorbed SO2. The secondary amine containing adsorbent, CA–S–MAPS, exhibits an improved stability and approximately 25% CO2 capacity loss is observed during cycling in the presence of SO2. Therefore, the secondary amine based CA–S–MAPS adsorbent demonstrates some degree of tolerance to SO2 in comparison to the CA–S–APS sample. Under humid conditions, SO2 imposes significant detrimental impacts on the two adsorbents, as a result of increased SO2 adsorption capacities in the presence of moisture. Although the CO2 uptake is nearly zero in the tertiary amine adsorbent, CA–S–DMAPS, the SO2 capacity of this adsorbent reaches 0.43 mmol/g under humid conditions and this material has the highest SO2/N ratio of the fiber adsorbents studied. More importantly, this CA–S–DMAPS sample demonstrates reversible SO2 adsorption, as indicated from the SO2 cyclic adsorption experiments. The tertiary amine based fiber adsorbents have good potential for flue gas desulfurization, with advantageous characteristics of high SO2/N ratio, excellent reversibility, low CO2 adsorption and relatively low regeneration temperature.

Finely tailoring the interfacial interaction to minimize the defective structure in the hybrid membranes is a key to yield a mixed matrix membrane with enhanced gas separation performance. Here, a highly selective mixed matrix membrane based on imidazole containing polyimides and ZIF-8 fillers is reported. The ZIF-8 with imidazole linker offers a more compatible interface with imidazole containing polyimides. At a MOF loading of 20 wt. %, the membranes have a 2.2-fold increase in the gas permeabilities over unfilled polymers with exceptional H2/CH4 and CO2/CH4 gas selectivities of 224 and 58, respectively. The H2 and CO2 gas permeabilities are 78.5 and 20.3 Barrer, respectively. The Zn2+ post-modification enables the formation of metal coordination crosslinking with enhanced polymer/ZIF-8 interaction, as indicated by increased glass transition temperature, improved thermal stability and insoluble properties in organic solvents. With the proper control of Zn2+ treatment conditions, gas permeabilities of H2 and CO2 can be increased to 110.1 and 27.4 Barrer, respectively, with the constant H2/CH4 and CO2/CH4 gas selectivity. For membranes treated at higher Zn2+ concentration, an enhancement in H2/CH4 gas selectivity was observed with the selectivity increasing from 223.9 to 318.3 and H2 permeability around 72.3 Barrer. The separation performance of H2/CH4 for all Zn2+ modified membranes exceeds the 2008 Robeson upper bound. This facile approach to tune polymer/MOF interaction via metal ion modification promotes the rational design of high-performance gas separation membranes.

Aiming at the problem of preferential competition of information caused by the fusion of terminal nodes and routing nodes in navigation satellite network, a terminal-prioritized network node transmission model is proposed. The characteristics of topology, routing, and service information path of the navigation satellite network was analyzed, and the terminal-first network node routing model and the mixed-preferred network node routing model was designed. Simulations based on the packet delivery delay and network throughput index show that the terminal-first network node routing model can achieve higher transmission performance.

The storage-carrying-forwarding of messages of the node is a way of short-distance communication in the mobile social networks, and the transmission performance is the key factor that affects the user interaction experience. If the user can transmit the message according to the interest or the community, the transmission performance can be improved. For the short-distance communication in the mobile social networks, the existing research is mainly either interest-based or community-based transmission. In order to make users to have a better interactive experience, we proposed InComT (Interest Community based Transmission) which combines the user interest with the community. We measure the interest value of a node in the mobile social networks, and the community is divided according to its interest value to determine the whole community interest value. Then the relay community and the relay node are selected by the interest value to realize the transmission of the message. The simulation results show that the scheme can get a higher transmission success rate with low transmission overhead and low average delay.

Uncertainty quantification plays a significant role in establishing reliability of mathematical models, while applying to process optimization or technology feasibility studies. Uncertainties, in general, could occur either in mathematical model or in model parameters. In this work, process of CO2 adsorption on amine sorbents, which are loaded in hollow fibers is studied to quantify the impact of uncertainties in the adsorption isotherm parameters on the model prediction. The process design variable that is most closely related to the process economics is the CO2 sorption capacity, whose uncertainty is investigated. We apply Bayesian analysis and determine a utility function surface corresponding to the value of information gained by the respective experimental design point. It is demonstrated that performing an experiment at a condition with a higher utility has a higher reduction of design variable prediction uncertainty compared to choosing a design point at a lower utility.

The dynamic CO2 sorption performance of polymer/silica supported polyethylenimine hollow fiber sorbents (CA-S-PEI), focusing on heat and mass transport effects, is investigated experimentally and computationally during sorption of CO2 from simulated, dry flue gases. The effect of the nonisothermality on the sorption performance is investigated by varying the module materials of construction. The heat effects are minimized by using a heat conductive module case with a diameter of 0.25 in., and, accordingly, the breakthrough capacities are increased by 30% over a similar module constructed from less conductive components, thereby improving fiber sorbents utilization efficiency. The sorption kinetics in CA-S-PEI hollow fiber sorbents are investigated in terms of flow rates, module packing fraction, module length, and silica particle size. A mathematical model developed previously is successfully utilized to predict various contributions to the overall mass transfer resistance. In fiber sorbents where the ami...

We described a facile and eco-friendly method for preparation of Pd nanocomposites (Pd-PDDA/RGO), which possesses a low Pd metal percent (20 wt%) and a mean size of 3.9 nm. The reaction was carried out at room temperature using Pd nanoparticles anchored on reduced graphene oxide (RGO) with the assist of poly(diallyldimethylammonium chloride). The Pd nanoparticles were well distributed without obvious aggregation. The Pd-PDDA/RGO nanocomposites exhibit higher electrocatalytic activity and stability for the electro-oxidation of ethanol than Pd/RGO, Pd-PDDA/MWCNTs (multi-walled carbon nanotubes) and Pd-PDDA/XC-72 carbon black. The peak current density for ethanol oxidation of Pd-PDDA/RGO is 1.38, 1.60 and 2.40 times stronger than that of Pd/RGO, Pd-PDDA/MWCNTs and Pd/XC-72, respectively.

A mathematical model is developed for carbon dioxide adsorption on hollow fiber post infused with physically impregnated poly(ethylenimine) silica sorbent. The model includes detailed mass transfer mechanisms and is rigorously validated under different operating conditions of flue gas flow rate, number of fibers within the module, fiber length and particle size. A fundamental model formulation for the sorbent polymer diffusivity including the temperature and the sorbent concentration dependency is proposed. The proposed model formulation is based on free volume theory model of polymer diffusion and effectively predicts the experimental observations. The model is able to predict the breakthrough curves at many different operating conditions and module designs such as conditions with varied flue gas flow rate, fiber length, fiber packing fraction and support silica particle size. The concave trend in the temperature dependency of breakthrough capacity that shows a maximum around 45–60 °C is analyzed using the developed model.

Individualized knowledge recommendation service has been widely applied and generalized in the big data environment, of which the foundation and core lies in the construction of user model. In this context, this paper emphatically studies the vector space model (VSM) representation-based user model construction by sorting out the concept and method of user model. The modeling process is also analyzed in detail from such aspects as user data classification, user characteristics model representation and similarity calculation, to conclude a user modeling-based individualized knowledge recommendation process with digital library as an example.

Amine-loaded poly(amide-imide) (PAI)/silica hollow fiber sorbents are created and used in a rapid temperature swing adsorption (RTSA) system for CO2 capture under simulated postcombustion flue gas conditions. Poly(ethylenimine) (PEI) is infused into the PAI/mesoporous silica hollow fiber sorbents during fiber solvent exchange steps after fiber spinning. A lumen-side barrier layer is also successfully formed on the bore side of PAI/silica hollow fiber sorbents by using a mixture of Neoprene with cross-linking agents in a post-treatment process. The amine loaded fibers are tested in shell-and-tube modules by exposure on the shell side at 1 atm and 35 °C to simulated flue gas with an inert tracer (14 mol % CO2, 72 mol % N2, and 14 mol % He, at 100% relative humidity (RH)). The fibers show a breakthrough CO2 capacity of 0.85 mmol/g-fiber and a pseudoequilibrium CO2 uptake of 1.19 mmol/g-fiber. When tested in the temperature range of 35-75 °C, the PAI/silica/PEI fiber sorbents show a maximum CO2 capacity at 65 °C, owing to a trade-off between thermodynamic and kinetic factors. To overcome mass transfer limitations in rigidified PEI infused in the silica, an alternate PEI infusion method using a glycerol/PEI/methanol mixture is developed, and the CO2 sorption performance is improved significantly, effectively doubling the functional sorption capacity. Specifically, the glycerol-plasticized sorbents are found to have a breakthrough and equilibrium CO2 capacity of 1.3 and 2.0 mmol/g of dry fiber sorbent at 35 °C, respectively. Thus, this work demonstrates two PAI-based sorbents that are optimized for different sorption conditions with the PAI/silica/PEI sorbents operating effectively at 65 °C and the PAI/silica/PEI-glycerol sorbents operating well at 35 °C with significantly improved sorption capacity.

The dynamic adsorption behavior of CO2 under both nonisothermal and nearly isothermal conditions in silica supported poly(ethylenimine) (PEI) hollow fiber sorbents (Torlon®-S-PEI) is investigated in a rapid temperature swing adsorption (RTSA) process. A maximum CO2 breakthrough capacity of 1.33 mmol/g-fiber (2.66 mmol/g-silica) is observed when the fibers are actively cooled by flowing cooling water in the fiber bores. Under dry CO2 adsorption conditions, heat released from the CO2-amine interaction increases the CO2 breakthrough capacity by reducing the severity of the diffusion resistance in the supported PEI. This internal resistance can also be alleviated by prehydrating the fiber sorbent with a humid N2 feed. The CO2 breakthrough capacity of prehydrated fibers is adversely affected by the release of the adsorption enthalpy (unlike the dry fibers); however, active cooling of the fiber results in a constant CO2 breakthrough capacity even at high CO2 delivery rates (i.e., high adsorption enthalpy delivery rates). In full RTSA cycles, a purity of 50% CO2 is achieved and the adsorption enthalpy recovery rate can reach ∼72%. Studies on the cyclic stability of uncooled fiber sorbents in the presence of SO2 and NO contaminants indicate that exposure to NO at 200 ppm over 120 cycles does not lead to a significant degradation of the sorbents, but SO2 exposure at a similar high concentration of 200 ppm causes 60% loss in CO2 breakthrough capacity after 120 cycles. A simple amine reinfusion technique is successfully demonstrated to recover the adsorption capacity in poisoned fiber sorbents after deactivation by exposure to impurities such SO2. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3878–3887, 2014

PbPt core–shell-like nanoparticles supported on graphene is successfully synthesized by a simply galvanic displacement reaction method. The composition, morphology, structure of the catalyst and activity towards methanol oxidation are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Chronoamperometric and CV results reveal that PbPt core–shell-like nanoparticles catalyst has better activity towards methanol oxidation than the pure platinum prepared under the same conditions. These behaviors are attributed to an electronic effect of the inner Pb or the increase in the d-orbital vacancy of Pt in core–shell-like PbPt catalyst.

The outstanding performance PtCu y (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCu y /rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCu y /rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCu y /rGO catalysts are concerned, the PtCu 2 /rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance.

The morphology and physical properties of a pentablock copolymer (PBC) were investigated as a function of sulfonation or ion-exchange capacity (IEC). This material is comprised t-butylstyrene (tBS), hydrogenated isoprene (HI), sulfonated polystyrene (sPS), and polystyrene (PS). Thermally reversible crosslinks are created with tBS, which is dispersed within a rubbery phase of HI, sPS, and PS. A morphology change was observed upon sulfonating PBC. This created abrupt material changes such as water swelling, proton conductivity, and methanol transport at an IEC greater than one. Water, proton, and methanol transport are associated with sPS domains. Gas transport occurs mainly through more permeable HI and tBS phases that were disrupted with increasing IEC. The permeability ( P ) was modeled using a lamellar morphology. Ion and methanol transport occurred via sulfonated domains. Finally, a structure–property and transport property correlation of this multi-block PBC ionomer is discussed within this paper.

Rapid temperature swing adsorption (RTSA) using polymer/silica supported amine hollow fiber sorbents is a new post combustion CO 2 capture methodology that facilitates CO 2 adsorption under nearly isothermal conditions with improved energy efficiency via heat integration. In this work, the dynamic CO 2 adsorption characteristics of polymer/silica supported poly(ethylenimine) hollow fiber sorbents (CA-S-PEI-PI) are evaluated in a bench scale RTSA system. Non-isothermal fibers have breakthrough and pseudo-equilibrium CO 2 capacities of 0.67 mmol/g and 1.03 mmol/g at 35 °C, respectively, under humid simulated flue gas conditions (100% R.H.). Prolonged exposure of the fiber sorbents to water vapor enabled the breakthrough and pseudo-equilibrium CO 2 capacities to increase by 60% and 43%, respectively. Upon the removal of the heat of adsorption by flowing cooling water in the bores of the fiber sorbents, there is a substantial increase in the CO 2 breakthrough capacity, reaching 1.16 mmol/g using simulated humid flue gases. The breakthrough capacity is found to increase 5% upon increasing the adsorption temperature from 35 °C to at 45 °C, suggesting improved mass transfer in the fiber sorbent at the higher temperature. The CO 2 adsorption and desorption rates are shown to be very rapid, with CO 2 breakthrough occurring in less than 72 s and the majority of the adsorbed CO 2 desorbing in 5 min. Extensive cycling studies demonstrate that the CA-S-PEI-PI sorbents have good dynamic swing capacities, stabilizing over 60 cycles. A newly developed rechargeable post-spinning amine infusion technique provides the feasibility of recovering the CO 2 adsorption performance of deactivated CA-S-PEI-PI fiber modules, by allowing for straightforward re-infusion of PEI into the deactivated sorbents. Amine-incorporated hollow fiber sorbents have good potential for practical use as scalable, adsorbing heat-exchangers.

The physical and transport properties of Li+, Na+, K+, and Ca2+ neutralized Nafion were compared to its acid form. Nafion crystallinity was disrupted with a variety of cations while average d-spacing remained constant. Higher thermal stability in metal ion exchanged Nafion was observed using TGA. Ionic interactions were probed by DMA and spectroscopic techniques. Divalent Ca2+ exhibited a distinctive influence on the chain’s mobility as compared to monovalent ions. The interaction strength cation exchanged Nafion decreased in the following order: Li+ > Ca2+ > Na+ > K+. Gas permeability increases were primarily attributed to gas solubility. Nafion had a higher gas activation energy Ep, but its permeability was lower than unsulfonated PTFE.

Taking the construction of STKOS (Science and Technology Knowledge Organization System) Service System in Intelligence 3.0 as the mainline, this paper first analyzes various functions that the system shall have, and designs the overall architecture of the system. Second, it introduces the implementation of the system from the perspectives of STKOS registration, triple retrieval, visual presentation and Web services. At last, it presents the key points in the future study.

Network coding can improve network throughput in large, but it is vulnerable to the data pollution attacks. In this paper, we propose an efficient homomorphic message authentication code (MAC) scheme with discrete logarithm to detect and locate the malicious nodes. We also prove the security property of the scheme theoretically. Its effectiveness is demonstrated, and overhead is analyzed through extensive experiments.

The gas transport and physical properties of sulfonated poly(arylene ether sulfone) was studied as a function of sulfonated and unsulfonated block length (5k:5k, 10k:10k, and 15k:15k). Viscoelastic properties were evaluated using Dynamic Mechanical Analysis (DMA) to observe polymer relaxations and domain compatibility. A decrease in glass transition temperature T g was observed with increasing block length. 5k:5k had a single T g (241 °C), while micro-phase separation between 10k:10k and 15k:15k domains create two T g 's that are slightly merged (191 °C, 236 °C and 182 °C, 233 °C). Swelling measurements revealed that film dimensional changes were greater in the plane normal to the film than parallel with increasing block size. He, H 2 , CO 2 , and O 2 permeability decreased with increasing sulfonated block length with no interchain spacing dependence. The apparent activation energy for permeation E p increased with gas kinetic diameter size and had a maximum value for 15k:15k. A trade-off relationship between sulfonated and unsulfonated polymer block length is linked to phase separation, water swelling, and gas permeability.

A series of poly(b-(t-butyl styrene)-b-(ethylene-co-propylene)-b-(styrene-co-styrene sulfonate)-b-(ethylene-co-propylene)-b-(t-butyl styrene)) ionomers were complexed with a series of metal ions. Raman sulfonate group symmetric ν s(SO3 −) and asymmetric ν as(SO3 −) stretching modes at 1031 and 1127 cm−1 were proportional to ion-exchange capacity. Mono and divalent counter-ions of Li+, Na+, K+, and Ca2+ affected the stretching modes of ν(SO3 −) due to ion size and charge. The gas permeability P and diffusivity D of O2, CO2, N2, and CH4 decreased with increasing complexation strength between sulfonate group and metal ion. Solubility S was a maximum for ionomers complexed with K+ and CO2, but small changes were observed for other metal ions. Overall, these results suggest that ionomers coordinated with different metal ions influence network physical properties, chain mobility, and gas transport.

A series of sulfonated poly(arylene ether sulfone) (BPSH-BPS) multiblock copolymer (MBC) ionomers were studied with respect to structure and physical properties. Ion exchange capacity (IEC w ) on a weight basis was constant for all MBC ionomers with controlled ionic and nonionic block lengths of 5k:5k, 10k:10k and 15k:15k. Viscoelastic properties were investigated as a function of block length, relaxation time, and temperature ranging from 200 °C to 250 °C. Relaxation time and glassy state modulus decreased with increasing ionic block length. Williams-Landel-Ferry (WLF) theory adequately modeled the viscoelastic changes in the BPSH-BPS MBC ionomers due to changes in time and temperature using a shift factor a T . Small Angle X-ray Scatter (SAXS) revealed an average inter-chain d -spacing that increased with increasing ionic block length (21.1, 31.4 and 36.4 nm). The larger ionic domain size is attributed to an increase in bulk ionic density within an ionic domain. Bondi’s group contribution method predicts a lower fractional free volume (FFV) with increasing ionic block length. The 15k BPSH-BPS MBC ionomer had the lowest FFV of the series, which corresponds to the lowest hydrogen permeability of 2.46 Barrers at 30 °C and 4 atm.

This project is a bench-scale, post-combustion capture project carried out at Georgia Tech (GT) with support and collaboration with GE, Algenol Biofuels, Southern Company and subcontract to Trimeric Corporation. The focus of the project is to develop a process based on composite amine-functionalized oxide / polymer hollow fibers for use as contactors in a rapid temperature swing adsorption post-combustion carbon dioxide capture process. The hollow fiber morphology allows coupling of efficient heat transfer with effective gas contacting, potentially giving lower parasitic loads on the power plant compared to traditional contacting strategies using solid sorbents.

The direct dual layer spinning of Torlon®/silica hollow fibers with a neat Torlon® lumen layer is reported here for the first time. The dual layer fibers containing a porous Torlon®/silica main structure and a dense, pure Torlon® polymer bore-side coating provide a simplified, scalable platform from which to construct hollow fiber amine sorbents for postcombustion CO2 capture. After fiber spinning, an amine infusion process is applied to incorporate PEI into the silica pores. After combining dilute Neoprene treatment followed by poly(aramid)/PDMS treatment, a helium permeance of the fiber sorbents of 2 GPU with a He/N2 selectivity of 7.4 is achieved. Ten of the optimized amine-containing hollow fibers are incorporated into a 22-inch long, 1/2 inch OD shell-and-tube module and the module is then exposed on the shell side to simulated flue gas with an inert tracer (14 mol % CO2, 72 mol % N2, 14 mol % He [at 100% R.H.]) at 1 atm and 35°C in a RTSA system for preliminary CO2 sorption experiments. The fibers are found to have a breakthrough and equilibrium CO2 capacity of 0.8 and 1.2 mmol/g- dry fiber sorbent, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41845.