117,787 research outputs found
Novel sol–gel preparation of (PO)–(CaO)–(NaO)–(TiO) bioresorbable glasses (X = 0.05, 0.1, and 0.15)
No full textQuaternary phosphate-based glasses in the PO–CaO–NaO–TiO system with a fixed PO and CaO content of 40 and 25 mol% respectively have been successfully synthesised via sol–gel method and bulk, transparent samples were obtained. The structure, elemental proportion, and thermal properties of stabilised sol–gel glasses have been characterised using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), P nuclear magnetic resonance (P NMR), titanium K-edge X-ray absorption near-edge structure (XANES), fourier transform infrared (FTIR) spectroscopy, and differential thermal analysis (DTA). The XRD results confirmed the amorphous nature for all stabilized sol–gel derived glasses. The EDX result shows the relatively low loss of phosphorus during the sol–gel process and Ti K-edge XANES confirmed titanium in the glass structure is in mainly six-fold coordination environment. The P NMR and FTIR results revealed that the glass structure consist of mainly Q and Q phosphate units and the Ti cation was acting as a cross-linking between phosphate units. In addition DTA results confirmed a decrease in the glass transition and crystallisation temperature with increasing NaO content. Ion release studies also demonstrated a decrease in degradation rates with increasing TiO content therefore supporting the use of these glasses for biomedical applications that require a degree of control over glass degradation. These sol–gel glasses also offer the potential to incorporate proactive molecules for drug delivery application due to the low synthesis temperature employed
Soft measurement method for f-CaO content of cement clinker
No full text本发明涉及水泥生产技术领域，尤其是涉及一种水泥熟料f-CaO含量软测量方法。本发明包括：选取生料的三率值、生料细度、煤粉热值、煤粉灰分、生料加料量、分解炉出口温度、窑电流和篦冷机的一篦床压力为辅助变量；对采集到的辅助变量的数据集合进行离群值去除、滤波和标准化，形成输入数据集合；对所述输入数据集合进行分类，对每个类分别建立部分最小二乘子模型和权重模型，再将每个子模型的输出进行加权平均得到最终的软测量结果；软测量模型校正：采用长期校正的方式对软测量模型进行校正。本发明能够测量出难以在线检测而又十分重要的熟料f-CaO含量，使水泥熟料烧成过程先进控制的实施成为可能
Process engineering and development of post-combustion CO2 separation from fuels using limestone in CaO-looping cycle
Full text linkGlobal CO2 emissions produced by energy-related processes, mainly power plants, have increased rapidly in recent decades; and are widely accepted as the dominant contributor to the greenhouse gas (GHG) effect and consequent climate changes. Among countermeasures against the emissions, CO2 capture and storage (CCS) is receiving much attention. Capture of CO2 is the core step of CCS as it contributes around 75% of the overall cost, and may increase the production costs of electricity by over 50%. The reduction in capture costs is one of the most challenging issues in application of CCS to the energy industry. Using limestone in CaO-looping cycles is a promising capture technology to provide a cost-effective separation process to remove CO2 content from power plants operations. Limestone has the advantage of being relatively abundant and cheap, and that has already been widely used as a sorbent for sulphur capture. However, this technology suffers from a critical challenge caused by the decay in the sorbent capture capacity during cyclic carbonation/calcination, which results in the need for more sorbent make-up; hence a reduction in cost efficiency of the technology. The performance of sorbent influenced by several operating and reaction conditions. Therefore, much research involves investigation of influencing factors and different methods to reduce the sorbent deactivation. Cont/d
Hybridisation of process-based ecosystem models with evolutionary algorithms: multi-objective optimisation of process and parameter representations of the lake simulation library SAMO-OO
No full textH. Cao and F. Recknagelhttp://www.witpress.com/978-1-84564-207-5.htm
Melt densities in the CaO-FeO-Fe2O3-SiO2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts
Full text linkThe densities of 10 melts in the CaO-FeO-Fe2O3-SiO2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO2, 14 to 76 wt% Fe2O3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy.
Melt densities range from 2.689 to 3.618 gm/cm3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe2O3 and SiO2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe3+.
The volume behavior of melts in this system is significantly different from that in the Na2O-FeO-Fe2O3-SiO2 system, consistent with the proposal that a proportion of Fe3+ in melts in the CaO-FeO-Fe2O3-SiO2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence (e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations.
The presence of more than one coordination geometry for Fe3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted
Simulated Experiment Study of Factors Influencing the Hydration Activity of f-CaO in Basic Oxygen Furnace Slag
Full text linkThe compositions and formation process of f-CaO in BOF slag were revealed and simulated to understand its expansion rules and why its hydration activity is low. BSE showed the compositions of f-CaO, which included calcium iron phase and calcium iron manganese phase, were diverse. The hydration activity sequence was Ca2Fe2O5 and Ca3Fe1.5Mn1.5O8 in tricomponent f-CaO < CaO in tricomponent f-CaO < monocomponent f-CaO; only Ca2Fe2O5 and Ca3Fe1.5Mn1.5O8 were hard to hydrate, and the volume expansion rates of the tricomponent f-CaO varied with different compositions. Inductively, in BOF slag, the hydration activity sequence was solid solutions CaO-FeOx and CaO-FeOx-MnOy in tricomponent f-CaO < CaO in tricomponent f-CaO < monocomponent f-CaO; the volume expansion rates of tricomponent f-CaO changed with different compositions, and CaO-FeOx and CaO-FeOx-MnOy were difficult to hydrate. The reason why solid solutions CaO-FeOx and CaO-FeOx-MnOy were hard to hydrate was that their hydration reaction driving force, which is the absolute value of standard molar reaction Gibbs functions, decreased
A new insight into the CaO-induced inhibition pathways on PCDD/F formation:Metal passivation, dechlorination and hydroxide substitution
No full textCa-based inhibitors (especially CaO) for PCDD/F (polychlorinated dibenzo-p-dioxin and dibenzofuran) formation are considered as economic inhibitors with low toxicity and strong adsorption of acidic gases (e.g., HCl, Cl2, and SOx), whereas the insight understanding of its inhibition mechanisms is scarcely explored. Herein, CaO was used to inhibit the de novo reaction for PCDD/F formation (250–450 °C). The evolution of key elements (C, Cl, Cu, and Ca) combined with theoretical calculations was systematically investigated. The concentrations and distribution of PCDD/Fs demonstrated the significant inhibition effect of CaO on I-TEQ (international toxic equivalency) concentrations of PCDD/Fs (inhibition efficiencies: > 90 %) and hepta~octa chlorinated congeners (inhibition efficiencies: 51.5–99.8 %). And the conditions (5–10 % CaO, 350 °C) were supposed to be the preferred conditions applied in real MSWIs (municipal solid waste incinerators). CaO significantly suppressed the chlorination of carbon matrix (superficial organic Cl (C[sbnd]Cl) reduced from 16.5 % to 6.5–11.3 %) and the formation of unsaturated hydrocarbons or aromatic carbon (superficial C[dbnd]C decreased from 6.7 % to 1.3–2.1 %). Also, CaO promoted the dechlorination of Cu-based catalysts and Cl solidification (e.g., conversion of CuCl2 to CuO, and formation of CaCl2). The dechlorination phenomenon was validated by the dechlorination of highly chlorinated PCDD/F-congeners (via DD/DF chlorination pathways). Density functional theory calculations revealed that CaO facilitated the substitution of [sbnd]Cl by -OH on the benzene ring to inhibit the polycondensation of the chlorobenzene and chlorophenol (Gibbs free energy reduced from +74.83 to −36.62 and − 148.88 kJ/mol), which also indicates the dechlorination effect of CaO on de novo synthesis.</p
Kapsa (Rigida) Cao & Zhang
No full textKey to males of Kapsa (Rigida) Cao & Zhang sgen. n. 1. Anal tube appendage rudimentary, small, not hooked at apex...................... K. apicispina Yang & Zhang sp. nov. - Anal tube appendage well developed, hooked apically (Figs 5 b, 6 b, 8 b, 9 b, 10 e, 11 c, 12 c, 13 c)........................ 2 2. Anal tube appendage curved cephalad in larteral view................................ K. maculata Sohi & Mann, 1992 - Anal tube appendage curved caudad in lateral view (Figs 5 b, 6 b, 8 b, 9 b, 10 e, 11 c, 12 c, 13 c)........................... 3 3. Aedeagus without ventral process near base of shaft (Figs 5 h, 6g, 11 i, 13g)........................................ 4 - Aedeagus with unpaired ventral process near base of shaft (Figs 8 h, 9g, 10 j, 12 i)................................... 7 4. Aedeagal shaft with ventral process near apex (Figs 6 g, 13g)................................................... 5 - Aedeagal shaft without process (Figs 5 h, 11 i)............................................................... 6 5. Paramere forked apically, with apical and basal branch, aedeagal shaft with small thornlike process ventro-apically (Fig. 6 e, g)...................................................................... K. aculeiformis Cao & Zhang sp. nov. - Paramere bifurcated apically, with dorsal and ventral branch, aedeagal shaft with large serrated protrusion ventro-medially (Fig. 13 e, g)................................................................ K. serrata Cao & Zhang sp. nov. 6. Apex of paramere straight, aedeagal shaft expanded in lateral view (Fig. 11 f, i)......... K. imminuta Yang & Zhang sp. nov. - Apex of paramere sinuate, aedeagal shaft not expanded in lateral view (Figs 5 e, f, h).......... K. alba Dworakowska, 1981 7. Ventral process not extended to midlength of aedeagal shaft (Figs 8 h, 9g)......................................... 8 - Ventral process surpassing midlength of aedeagal shaft (Figs 10 j, 12 i)........................................... 10 8. Paramere footlike apically, heel expanded, ventral processes of aedeagus rounded in lateral view (Fig. 9 e, g)...................................................................................... K. explanata Cao & Zhang sp. nov. - Paramere with second extension apically, ventral processes of aedeagus pointed in lateral view (Fig. 8 h, i)............... 9 9. Aedeagal shaft expanded in lateral view, almost straight............................... K. minuta Dworakowska, 1994 - Aedeagal shaft not expanded in lateral view, obviously curved ventrad (Fig. 8 h)........... K. brevis Cao & Zhang sp. nov. 10. Ventral process of aedeagus with broadened and concave apex in caudal view....... K. borealis Dworakowska & Sohi, 1978 - Ventral process of aedeagus pointed apically in caudal view (Figs 10 k, 12 j)....................................... 11 11. Paramere forked apically (Fig. 10 h).............................................. K. furcata Cao & Zhang sp. nov. - Paramere not forked apically (Fig. 12 g)................................................................... 12 12. Aedeagus with base of ventral process broader than that of shaft in lateral view (Fig. 12 i).................................................................................................. K. megaprocessa Cao & Zhang sp. nov. - Aedeagus with base of ventral process slightly narrower than that of shaft in lateral view......................................................................................... K. simlensis Dworakowska, Nagaich & Singh, 1978Published as part of Yang, Meixia, Cao, Yanghui & Zhang, Yalin, 2013, Taxonomic study of the genus Kapsa Dworakowska with a new subgenus, and new combinations and records for Tautoneura Anufriev (Hemiptera: Cicadellidae: Typhlocybinae: Erythroneurini), pp. 117-142 in Zootaxa 3630 (1) on page 128, DOI: 10.11646/zootaxa.3630.1.4, http://zenodo.org/record/22287
Bidirectional branch and bound for controlled variable selection. Part II: exact local method for self-optimizing control
Full text linkThe selection of controlled variables (CVs) from available measurements through
enumeration of all possible alternatives is computationally forbidding for
large-dimensional problems. In Part I of this work [Cao, Y., & Kariwala, V.
(2008). Bidirectional branch and bound for controlled variable selection: Part
I. Principles and minimum singular value criterion. Comput. Chem. Eng., 32
(10),2306-2319], we proposed a bidirectional branch and bound (BAB) approach for
subset selection problems and demonstrated its efficiency using the minimum
singular value criterion. In this paper, the BAB approach is extended for CV
selection using the exact local method for self-optimizing control. By
redefining the loss expression, we show that the CV selection criterion for
exact local method is bidirectionally monotonic. A number of novel determinant
based criteria are proposed for fast pruning and branching purposes resulting in
a computationally inexpensive BAB approach. We also establish a link between the
problems of selecting a subset and combinations of measurements as CVs and
present a partially bidirectional BAB method for selection of measurements,
whose combinations can be used as CVs. Numerical tests using randomly generated
matrices and binary distillation column case study demonstrate the computational
efficiency of the proposed methods. (C) 2009 Elsevier Ltd. All rights reserved
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