Search

Equivalence ratio is one of the important operating parameters for biomass gasification. The oxygen carrier possesses high producer gas production in a wide range of equivalence ratio (oxygen carrier/biomass ratio), which is exceedingly desirable for biomass chemical looping gasification (CLG). In this study, the effect of different equivalence ratios on the CO selectivity (the evolved gas composition) of Fe2O3, Fe2O3/CaO and CaFe2O4 oxygen carriers in biomass char CLG was investigated in a fixed bed reactor. The results showed that the CO selectivity of CaFe2O4 had little changes and decreased from 70.39% to 59.79% and 73.40% to 63.98% with increasing equivalence ratio from 0.5 to 3.0 at 900 °C and 1000 °C, respectively. In sharp contrast, the CO selectivity of Fe2O3 changed markedly, which declined respectively from 65.86% to 31.13% (900 °C) and 69.68% to 47.27% (1000 °C). Fe2O3/CaO illustrated the similar tendency as Fe2O3 at 900 °C but as CaFe2O4 at 1000 ℃. The three oxygen carries exhibited a high CO production at lower equivalence ratio, and CaFe2O4 displayed the best performance of CO selectivity in the given equivalence ratio range. X-ray diffraction (XRD) spectrums showed that the oxygen carriers were transformed to different iron phases with difference equivalent ratios. The Fe (III) in the three oxygen carries was reduced completely to Fe (0) at the equivalence ratios of 0.5 and 1.0, while FeO and Ca2Fe2O5 were the dominant species in the spent oxygen carriers as equivalence ratio was further increased. The trends of CO selectivity obtained by thermodynamic analysis for three oxygen carries were consistent with the experimental results.

Non-petroleum route to produce transportation fuels is alternative way to address the fast depletion of the crude oil reservoir, especially in China. In this work, series of nanocrystal H[Fe, Al]ZSM-5 zeolite samples with different SiO2/Al2O3 ratio were prepared with hydrothermal method using sodium aluminate and tetraethyl orthosilicate as Al and Si sources, respectively, and the tetrapropylammonium hydroxide was used for structure-directing agent (SDA). The synthesized zeolites were characterized in detail by UV–Vis, X-ray diffraction, scanning electron microscope, N2 sorption, X-ray fluorescence, ammonia temperature-programmed desorption and pyridine-FTIR techniques. Fe species were incorporated into ZSM-5 framework, resulting in the formation of some new active sites. For the Iron-containing nanocrystal ZSM-5 samples with different SiO2/Al2O3 ratio, the B and L acid strength and amounts are determined by the coexistence and synergistic effect of Al- and Fe-based acid sites. The catalytic results illustrated that the H[Fe, Al]ZSM-5 zeolite with SiO2/Al2O3 ratio for 45 exhibited the best catalytic activity and stability due to its maximum B acid amount and higher B/L ratio. The DME conversion remains at >98% within the 135 h investigation. Moreover, the gasoline yield was up to 72.5%, and the selectivity for aromatics and durene could be reduced to 40% and 1%, respectively.

The deformation of blades under complex loads of multiple working conditions will reduce the energy conversion efficiency. To reduce the deviation of the blade shape in practical working conditions, a combination and optimization method of blade design schemes under multiple working conditions, based on the entropy weight vague sets, is proposed. The sensitivity of each working condition index is analyzed based on the information entropy, and the satisfaction degree of the design scheme based on the design requirements and experiences is described with the vague set. The matching degree of different design schemes for multiple working conditions is quantified according to the scoring function. The combination and optimization of the design scheme are verified by numerical simulation analysis. The results show that the proposed design scheme has a smaller blade shape deviation than the traditional design scheme under multiple working conditions.

Chemical looping reforming/gasification of toluene, the model compound representing biomass tar, was studied by using two oxygen carriers, 2CuO-2NiO/Al2O3 (molar ratio) and CaFe2O4. Their reaction performances were evaluated in a TG-FTIR and a laboratory-scale fixed bed reactor. The active lattice oxygen of the 2CuO-2NiO/Al2O3 oxygen carrier demonstrated excellent reactivity and completely oxidized toluene to CO2 at 600–700 °C, while the fixed bed reactor data indicated that 2CuO-2NiO/Al2O3 oxygen carrier could catalyze the cracking of toluene to produce H2 after loss of lattice oxygen. The CaFe2O4 oxygen carrier exhibited a good performance of chemical looping partial oxidation of toluene to CO and H2 with a fairly high reactivity. Over CaFe2O4 oxygen carrier, the CO and H2 dominated reaction products in the temperature range of 800–900 °C except at the startup stage. Catalytic cracking of toluene by CaFe2O4 to produce H2 was also observed after partial loss of lattice oxygen. Stable performance of CaFe2O4 with high reactivity to syngas (CO and H2) was demonstrated during a 3-cyle test in the fixed bed reactor. After reduction of action with toluene, scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated that 2CuO-2NiO/Al2O3 was reduced to metallic copper and nickel with the mixture of NiAl2O4, and CaFe2O4 was reduced to metallic iron and CaO. In summary, two oxygen carriers displayed high toluene conversion at the beginning stage and the conversion of toluene increased to about 100% in the subsequent stage.

Catalytic upgrading of anisole and guaiacol in an atmospheric dielectric barrier discharge (DBD) plasma reactor was studied. Compared to thermal upgrading in a fixed bed, the DBD plasma method can convert the model compound to benzene and toluene with high selectivity under relatively low temperature. The synergistic effect between H2 plasma and Ni-Mo/SiO2 catalyst is crucial to the high deoxygenation rate. The primary reactions occurring during the DBD upgrading process include demethylation, methyl transfer, and hydrogenolysis. XRD spectra indicate that phase change should not be the primary reason for catalyst deactivation; GC–MS, NH3-TPD, and regeneration experiments show that carbon deposition is the cause for deactivation. NH3-TPD analysis reveals that a combination of medium and strong acid sites plays an important role in the hydrogenolysis of phenols to benzenes. The present work shows DBD catalytic upgrading as a promising route for the C O bond hydrogenolysis reaction.

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, are very convenient precursors with a tunable flexibility toward multifunctional nanomaterials, especially in energy storage. Typical methods to improve lithium storage are to introduce additional or self-generating carbonaceous supports to LDH-derived transition metal oxides as anode nanomaterials which can host lithium mainly though a conversion mechanism. Here, we describe a preparation of mesoporous spinel ferrite composite (MgFe 2 O 4 /ZnFe 2 O 4 ) for lithium storage, which is assisted by a combined conversion and alloying mechanism. The composite is derived by a thermal decomposition of a scalablely produced single-resource precursor of ternary Mg 2+ Zn 2+ Fe 3+ -layered double hydroxide (Mg 2+ Zn 2+ Fe 3+ -LDH), and subsequent selective etching. Electrochemical test shows that the electrode delivers an exceptional electrochemical performance, i.e., a reversible capacity of 1190 mA h g −1 after 100 cycles at 100 mA g −1 , and, in particular, a reversible capacity of 981 mA h g −1 at 500 mA g −1 after 330 cycles, as well as a reversible capacity of 541 mA h g −1 at 2000 mA g −1 after 1000 cycles. The high electrochemical performance could be attributed to the following features: the combined alloying and conversion mechanisms of ZnFe 2 O 4 , synergistic MgFe 2 O 4 , and slight-content MgO as a non-active matrix, as well as an appropriate specific area and mesoporous size distribution. Our results show that the cation-tunable LDH precursor-derived synthesis route might be an alternative to prepare multiple-component composites of spinel ferrites and transition metal oxides.

Although pre-column derivatization with n-propylamine and acetic anhydride combined with the gas chromatograph was a useful method for the analysis of monosaccharide composition, failure often occurs because of lack of detail information on the mechanism as well as the operating key point in derivatization process. In this study, the key points in the derivatization (lactonization time, the amount of n-propylamine and acetic anhydride) were investigated and optimized to improve the method. Under the optimal conditions, the derivatives of seven neutral monosaccharides and two uronic acids were simultaneouly obtained, after which they were well separated and detected by GC. It was also found that all derivatives of monosaccharides were stable even stored for 20days. The linearity, sensitivity, precision, reproducibility and recovery rate of the improved method were evaluated. Thereafter, five polysaccharide samples from different sources were analyzed to validate the improved method.

Model counting is the problem of computing the number of models or satisfying assignments for a given propositional formula, and is # P -complete. Owing to its inherent complexity, approximate model counting is an alternative in practice. Model counting using the extension rule is an exact method, and is considered as an alternative to resolution-based methods for model counting. Based on the exact method, we propose two approximate model counting algorithms, and prove the time complexity of the algorithms. Experimental results show that they have good performance in the accuracy and efficiency.

Based on a promising process of biomass to liquid (BTL) fuels, a pilot-scale plant including gasification, direct synthesis of dimethyl ether (DME) and DME to gasoline was developed. The evaluations of the designed facilities and the optimization of the operation parameters for the whole system were carried out. The several running tests demonstrated the feasibility of converting biomass to high octane gasoline in the developed pilot plant. The adopted critical components of the facilities were verified and the anticipated design goal was achieved. The operating results showed that both the pressure and gas hourly space velocity (GHSV) not only influenced the CO conversion and the DME yield, but also had a significant effect on the manipulation of the reaction heat in the adiabatic reactor. High pressure and low GHSV favored the high CO conversion and the DME yield. Considering CO conversion and temperature controlling of the adiabatic reactor, the optimized pressure and GHSV of the synthesis process were 2.2–2.5 MPa and 1200 h−1, respectively. The per-pass conversion of CO and the production capacity of gasoline were about 45% and 4.4 kg/h, respectively under this condition.

With increasing energy demand and environmental problems in China, energy gases, such as natural gas(NG), coalbed methane(CBM) and coke-oven gas(COG) are alternatives of coal with great potential due to abundant reserves and remarkable environmental superiority for carbon reduction. Based on a large number of sampling data derived from comprehensive field investigations, energy gases used in China are researched on their compositions, net calorific values(NCVs), resources distributions and annual productions firstly in this paper, and then the Chinese-specific carbon contents by gas type and consuming sector are calculated to establish basic data for accurate estimation of carbon emissions. Results show that Chinese-specific carbon contents for NG, CBM and COG are 15.19 kg/GJ [15.15–15.37 kg/GJ], 15.13 kg/GJ [14.72–15.39 kg/GJ] and 11.41 kg/GJ [9.95–12.34 kg/GJ], respectively. Compared to IPCC, both carbon contents of NG and CBM are in close proximity to the default value, while COG has an obviously lower carbon content. Little difference exists among carbon contents of NG utilized in four main sectors including industry, power generation, households and vehicles, while a relatively obvious difference exists among those of COG. Carbon emissions would be greatly reduced by increasing the share of gas consumption in each sector. The market circumstances, application technologies, development bottlenecks as well as emission reduction potentials are studied respectively for the four utilization sectors with bright prospects. Finally, effective policy recommendations are given on the development of energy gases for the purpose of achieving a win-win of economy and environment.

The pyrolysis processes of the selected combustible solid wastes (CSWs) including poplar wood, polyethylene (PE), paper, rubber, rice and polyethylene terephthalate (PET) were investigated by thermogravimetric (TG) analysis. The pseudocomponents of the six kinds of selected CSWs were determined based on Weibull mixture model. The DAEM reaction model was used to study the pyrolysis kinetics of the samples. The results showed that the pyrolysis temperature of selected CSWs was ranged from 413.15 to 979.14 K and the Weibull mixture model can reproduce the TG and DTG curves accurately. The TG curve can be understood as a sum of two or three parallel reactions, where each single reaction was represented by one Weibull model component. It was observed that there were three pseudocomponents for the poplar and paper samples. There was one pseudocomponent for the PE sample. However, the rubber, rice and PET samples had two pseudocomponents. The activation energy (E α ) changed from 120 to 225 kJ mol−1 in the range of the conversion rate from 0.15 to 0.85 for the six kinds of selected CSWs.

To investigate the lignin pyrolysis mechanism, two α-O-4 and one completely substituted β-O-4 lignin dimeric model compounds were studied using in situ synchrotron vacuum ultraviolet photoionization time-of-flight mass spectrometry (SVUV PIMS) at 350–500 °C. The collision-reduced vacuum condition, in situ characteristic, and “soft” ionization technique of this reactor system allowed for the direct detection of thermolysis radicals and high-boiling-point compounds. For the α-O-4 compound 4-(benzyloxy)phenol (BOP) pyrolysis, benzyl radical, p-semiquinone radical, toluene, and bibenzyl were confirmed, supplying firm evidence for the free radical dominant mechanism. Experiments of the p-methoxy substituent on the hydroxyl position of BOP show that the p-methoxy substituent can lower the Caromatic–Cα and Oether–Caromatic bond dissociation energies. For β-O-4 compound guaiacylglycerol-β-guaiacyl ether (GGGE), it is inferred that the C–O homolysis mechanism was minor and the concerted reaction dominated in the e...

With the rapid development of high-throughput sequencing technologies, huge volumes of generated cancer genomics data make it into reality to understand the carcinogenic pathogenesis from the molecular level. It is believed that the study of commonalities among different cancers is one of the significant problems for understanding cancers, and will be beneficial for personalized therapy and precision medicine in cancer treatment. The ComMDP method is a useful one for solving this problem. However, when there is a substantially difference among the number of samples, the method of accumulating the absolute weight value of every cancer, employed by the ComMDP method, may give rise to missing some driver pathways. In this paper, two mathematical models CDP-V and CDP-H, replacing the absolute weight values with relative ones, are presented by using variance and harmonic mean, respectively. By devising a sort of short chromosome code and a greedy based recombination operator, a parthenogenetic algorithm is proposed for solving these two models. Extensive experiments were performed on both simulated and real cancer data. The experimental results show that given several types of cancer, the gene sets identified based on the presented models and algorithm not only mutate in a large proportion of samples of these cancers, but have close proportion of mutated samples in each cancer. In addition, some biologically meaningful gene sets, which are missed by the ComMDP one, are indeed detected. Hence the identified methods based on the presented models and algorithm may become useful complementary tools for identifying cancer pathways.

Knowledge representation and reasoning is one of the most important topics in the field of artificial intelligence. Classical 2-valued logic is often used for representation and reasoning of precise knowledge. However, in practical applications, intelligent systems need to understand and handle knowledge involving time and fuzzy concepts, which classical 2-valued logic cannot do well. To this end, in this paper we propose a 2n-valued temporal logic for representing and reasoning of temporal, fuzzy knowledge. Moreover, we discuss the characteristics of the logic, including some of theorems that hold in the classical logic as well as some unique to the logical proposed. Finally, we give an example of the impact of seasonal cooling on influenza to show how our logic can be used in practice.

It is crucial to appropriately deploy Roadside Units (RSUs) to guarantee the QoS of Vehicle-to-Infrastructure communication. Sarubbi et al. proposed the Delta-r algorithm by using relative contact time to meet the \(\triangle _{\rho _{2}}^{\rho _{1}}\)-Deployment, which is a metric for evaluating the performance of VANET. However, the “false high” relative contact time might play a negative effect on decision-making. In this paper, an improved algorithm Delta-uc, which is based on Useful Contribution, is presented. It avoids the negative effect of “extra” contact time by retaining only the useful relative trip duration of a vehicle at an urban cell. In addition, based on the Delta-uc algorithm, an effective recombination operator is designed, and a parthenogenetic algorithm UCPGA is proposed to solve the deployment problem. Compared with algorithms Delta-r and Delta-GA, in many \(\triangle _{\rho _{2}}^{\rho _{1}}\)-Deployments, the Delta-uc and UCPGA algorithms respectively required fewer RSUs, which were proved by the experiments on the realistic mobility trace of Cologne, Germany.

Nowadays, more and more applications are dependent on storage and management of semi-structured information. For scientific research and knowledge-based decision-making, such data often needs to be published, e.g., medical data is released to implement a computer-assisted clinical decision support system. Since this data contains individuals’ privacy, they must be appropriately anonymized before to be released. However, the existing anonymization method based on l-diversity for hierarchical data may cause a serious similarity attack, and cannot protect data privacy very well. In this paper, we utilize fuzzy sets to divide levels for sensitive numerical and categorical attribute values uniformly (a categorical attribute value can be converted into a numerical attribute value according to its frequency of occurrences), and then transform the value levels to sensitivity levels. The privacy model ( α l e v h , k)-anonymity for hierarchical data with multi-level sensitivity is proposed. Furthermore, we design a privacy-preserving approach to achieve this privacy model. Experiment results demonstrate that our approach is obviously superior to existing anonymous approach in hierarchical data in terms of utility and security.

The minimum error correction (MEC) model is one of the important computational models for determining haplotype information from sequencing data, i.e., single individual single nucleotide polymorphism (SNP) haplotyping, haplotype reconstruction or haplotype assembly. Due to the NP-hardness of the model, a fast and accurate enumeration algorithm is proposed for solving it. The presented algorithm reconstructs the SNP sites of a pair of haplotypes one after another. It enumerates two kinds of SNP values, i.e., (0 1)T and (1 0)T, for the SNP site being reconstructed, and chooses the one with more support coming from the SNP fragments that are covering the corresponding SNP site. The experimental comparisons were conducted among the presented algorithm, the FAHR, the Fast Hare and the DGS algorithms. The results prove that our algorithm can get higher reconstruction rate than the other three algorithms.