scholarly journals Improvements in Recovery Efficiencies of Phenols from Phenol Fraction Using Two-Stage Alkali Treatment

2021 ◽  
Vol 65 (2-4) ◽  
pp. 442-445
Author(s):  
G.V.S. Sarma ◽  
P. Bala Bharathi ◽  
J.V.S. Murty ◽  
G.M.J. Raju ◽  
K.V. Ramesh ◽  
...  
Keyword(s):  
Alkali Treatment ◽  
Maximum Yield ◽  
Steel Plant ◽  
Single Stage ◽  
Alkali Solution ◽  
Two Stage ◽  
Second Stage ◽  
Alkali Solutions ◽  
Distillation Plant ◽  
Phenol Fraction

Experiments were carried out for the recovery of phenols from phenol fraction procured from tar distillation plant of Visakhapatnam steel plant by two stage alkali treatment, to study the effect of two-stage alkali treatment on the yield of phenols from phenol fraction. The results of the present investigation showed that two-stage alkali wash gives better yields of phenols compared to single stage alkali wash of the same phenol fraction with the same strength of alkali solution (NaOH). Also it is shown that maximum yield of phenols could be obtained with 35% strength of alkali. In the first stage 70% of 35% strength solution was used while in the second stage treatment 30% of the same strength solution was used. Improvements in the recovery efficiencies of phenols were found to be 47% more than those reported earlier in the single-stage extraction studies for the same strength of alkali solutions.

Two-stage thermophilic-mesophilic anaerobic digestion of waste activated sludge from a biological nutrient removal plant

2006 ◽  
Vol 53 (8) ◽  
pp. 149-157 ◽  
Author(s):  
S. Watts ◽  
G. Hamilton ◽  
J. Keller
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Treatment Plant ◽  
Single Stage ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Two Stage ◽  
Primary Sludge ◽  
Second Stage

A two-stage thermophilic-mesophilic anaerobic digestion pilot-plant was operated solely on waste activated sludge (WAS) from a biological nutrient removal (BNR) plant. The first-stage thermophilic reactor (HRT 2 days) was operated at 47, 54 and 60 °C. The second-stage mesophilic digester (HRT 15 days) was held at a constant temperature of 36–37 °C. For comparison with a single-stage mesophilic process, the mesophilic digester was also operated separately with an HRT of 17 days and temperature of 36–37 °C. The results showed a truly thermophilic stage (60 °C) was essential to achieve good WAS degradation. The lower thermophilic temperatures examined did not offer advantages over single-stage mesophilic treatment in terms of COD and VS removal. At a thermophilic temperature of 60 °C, the plant achieved 35% VS reduction, representing a 46% increase compared to the single-stage mesophilic digester. This is a significant level of degradation which could make such a process viable in situations where there is no primary sludge generated. The fate of the biologically stored phosphorus in this BNR sludge was also investigated. Over 80% of the incoming phosphorus remained bound up with the solids and was not released into solution during the WAS digestion. Therefore only a small fraction of phosphorus would be recycled to the main treatment plant with the dewatering stream.

Efficiency Improvement in Entrained Flow Gasification

2011 ◽  
Author(s):  
Ankit Bhatnagar ◽  
S. Pushpavanam
Keyword(s):  
Oxygen Consumption ◽  
Single Stage ◽  
Stage Model ◽  
Two Stage ◽  
Entrained Flow ◽  
Second Stage ◽  
Cold Gas Efficiency ◽  
Stage System ◽  
Gas Efficiency ◽  
Cold Gas

In this work a one dimensional steady state model is developed for a single stage and two-stage bottom fed entrained flow coal gasifier for. The single stage model was first analysed for two different oxidants (i) oxygen and (ii) air to study their effects on gasification. Analysis proved oxygen to be the better oxidant. The model is then extended to a two stage gasifier. Here 30 (70) percent of the coal is fed in the first stage (second stage). The first (second) stage operates in oxidant rich (lean) environment. The performances of single stage and two-stage models are compared in terms of their cold gas efficiencies for the same coal feed rates. It is observed that a two-stage system has better cold gas efficiency (77%) than a single stage system (72%) with lower oxygen consumption. The two-stage model is used to optimise the O2/Coal ratio as the H2O/Coal ratio is varied in the 2nd stage. The optimum yields the highest cold gas efficiency with minimum possible oxygen consumption.

The Static Stability of a Cone-Cylinder Flare and Two Cone-Cylinder Fin-Flare Combinations at Supersonic Speed

1969 ◽  
Vol 73 (702) ◽  
pp. 520-524
Author(s):  
M. C. Mathur
Keyword(s):  
Static Stability ◽  
Single Stage ◽  
Sounding Rocket ◽  
Supersonic Speed ◽  
Aerodynamic Stability ◽  
Two Stage ◽  
Second Stage ◽  
Black Brant

The Black Brant IV shown in Fig. 1, is a two-stage sounding rocket with a 15KS-25 000 booster motor stabilised with three fins and a 9KS-11 000 motor, a 5·3 fineness ratio conical noise and an 11·5° conical flare forming the second stage. Basically, the second stage is the single stage Black Brant III rocket, but uses a conical flare instead of three fins at the aft end for aerodynamic stability. This paper reviews the static stability of a Black Brant IV second stage with a flare and two fin-flare combinations.

scholarly journals Asymptotic Genetic Response Due to Two-Stage Genomic Index Selection Derived from Correlated or Independent Indices during Both Stages

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Togashi K ◽  
Adachi K ◽  
Kurogi K ◽  
Watanabe T ◽  
Toda S ◽  
...  
Keyword(s):  
Genetic Variance ◽  
Absolute Magnitude ◽  
Path Selection ◽  
Single Stage ◽  
Index Selection ◽  
Genetic Response ◽  
Two Stage ◽  
Second Stage ◽  
Economic Weights ◽  
Economic Weight

We developed equations to predict the asymptotic response due to two-stage selection, where first-stage selection was performed by using GEBVs based solely on genotypes and second-stage selection was performed with GEBVs that combined genotypes and phenotypes. The situation that we considered involved four-path selection executed as sires to breed sons, sires to breed daughters, dams to breed sons, and dams to breed daughters. We established two procedures to predict the response. The first incorporated correlated indices during the first and second-stage selections of two-stage selection. The other procedure used independent indices during two-stage selection. The response per generation in the initial generation was greater for the correlated indices than for the independent indices. However, the asymptotic response per generation was slightly greater for the independent indices than for the correlated indices. The asymptotic response per generation was lower during two-stage selection than during single-stage selection. However, the asymptotic response per year was greater for two-stage selection than for single-stage selection. In addition, that trend was more conspicuous when the economic weight was 1:3 for the first (h2 =0.3) to second (h2 =0.05) index trait compared with economic weights of 1:1 and 3:1. However, the magnitude of the response to the aggregate genotype-relative not to single-stage selection but to absolute magnitude was greater at an economic weight of 3:1 than at those of 1:1 and 1:3. The reduction in genetic variance from the initial to an asymptotic generation was greater for a scenario where young parents selected at the first-stage accounted for 30% of all parents in two-stage selection than where they accounted for 70%. The reduction in genetic variance of the aggregate genotype over generations was smaller for independent indices than correlated indices during two-stage selection. Our new formula for predicting genetic response applies to any combination of accuracies of GEBVs and intensities of selection. Therefore, the formula presented is a general equation for predicting genetic response over generations due to two-stage genomic index selection.

Effects of Two-Stage Solution Heat Treatments on Microstructures and Properties of Cu-Cr-Zr Alloy

2013 ◽  
Vol 423-426 ◽  
pp. 230-234 ◽  
Author(s):  
Hao Feng Xie ◽  
Li Jun Peng ◽  
Zeng Hui Wang ◽  
Xu Jun Mi
Keyword(s):  
Tensile Testing ◽  
Solution Treatment ◽  
Heat Treatments ◽  
Single Stage ◽  
Solution System ◽  
Two Stage ◽  
Second Stage ◽  
Pure Matrix ◽  
System 1 ◽  
Zr Alloy

Novel two-stage solution heat treatments were applied to Cu-Cr-Zr alloy to improve its properties. The influences of these treatments on the microstructures and properties of the alloy were investigated by TEM, SEM, tensile testing and electrical conductivity test. The investigation showed that with the proposed solution treatments, it was possible to obtain better properties than the properties obtained by conventional single-stage solution treatment. For example, in the case of an alloy of Cu-0.4wt.%Cr-0.1wt.%Zr, it was found that a two-stage solution treatment system (8 h at 920 °C followed by 1 h at 1010 °C) produced better combination property than the conventional single-stage solution system (1 h at 950 °C) applied by other researchers. The first stage solution treatment is crucial to the dissolution of CuZr precipitates, dissolved CuZr phase completely, at the same time precipitated Cr phase. Subsequently, excess Cr precipitates all dissolved at the second stage solution treatment. As a result, a pure matrix is obtained after such two-stage solution heat treatments.

scholarly journals Change of anthocyanins content during raspberry extraction

2003 ◽  
Vol 48 (1) ◽  
pp. 85-102 ◽  
Author(s):  
Predrag Vukosavljevic ◽  
Branka Bukvic ◽  
Miodrag Jankovic ◽  
Snezana Masovic
Keyword(s):  
Heat Treatment ◽  
Operating Conditions ◽  
Single Stage ◽  
Two Stage ◽  
Second Stage ◽  
Stage 4 ◽  
Total Anthocyanins ◽  
Negative Effect

Change in anthocyanins content under different conditions of extraction enzymatic maceration and heat treatment of two raspberry cultivars (Villamette and Meeker) was determined. Experiments were carried out on a laboratory hydraulic extractor. During extraction commercial operating conditions were emulated using a "Bucher" extractor (pressure 180-200 bar 1-3 pulp shakings). A pectin preparation Klerzyme?120, manufactured by DSM France, was used for maceration and depectinization, because it is specific for "sour fruits" with pH below 3.2. At a single-stage maceration, it was applied in the amount of 200-400 g/t, for 1-2 hours at 50oC. In a two-stage maceration and depectinization, the enzyme was added as follows: in the first stage 100-200 g/t for 0.5 - 1 hour at 20oC and in the second stage 4-8 g/hl for 1-2 hours at 200C. Thermal breaks of raspberry pulp were performed at raised temperatures for 2 and 5 min in order to examine the effects of raised temperatures on anthocyanins extraction. The application of heat-enzymatic treatments of the pulp prior to extraction proved to be suitable in both raspberry cultivars. Apart from well-known degrading effects of heat on anthocyanins, the juice obtained by extraction, after enzymatic maceration, has higher anthocyanins content by 30% than the juice obtained without enzymatic maceration. Juice pasteurization, in each stage of processing, produced markedly negative effect on anthocyanins content therefore their content decreases considerably. The forms of anthocyanins that are lost most are those uncolored. In batches subjected to a two -stage enzymatic maceration, despite initial high anthocyanins content, the content of total anthocyanins is reduced after the second pasteurization to the approximate value as that in batches subjected to a single-stage enzymatic maceration.

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

An Enhanced Two Stage MMSE Equalizer for Coded FBMC/OQAM Systems

2019 ◽  
Vol 10 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Mohammad Rizk Assaf ◽  
Abdel-Nasser Assimi
Keyword(s):  
Error Propagation ◽  
Channel Model ◽  
Error Correcting Codes ◽  
Two Stage ◽  
Probability Of Error ◽  
Second Stage ◽  
Different Types ◽  
Mmse Equalizer ◽  
And Performance ◽  
Ici Cancellation

In this article, the authors investigate the enhanced two stage MMSE (TS-MMSE) equalizer in bit-interleaved coded FBMC/OQAM system which gives a tradeoff between complexity and performance, since error correcting codes limits error propagation, so this allows the equalizer to remove not only ICI but also ISI in the second stage. The proposed equalizer has shown less design complexity compared to the other MMSE equalizers. The obtained results show that the probability of error is improved where SNR gain reaches 2 dB measured at BER compared with ICI cancellation for different types of modulation schemes and ITU Vehicular B channel model. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.

Personalised attraction recommendation for enhancing topic diversity and accuracy

2021 ◽  
pp. 016555152199980
Author(s):  
Yuanyuan Lin ◽  
Chao Huang ◽  
Wei Yao ◽  
Yifei Shao
Keyword(s):  
Real World ◽  
Information Overload ◽  
Two Stage ◽  
Misclassification Cost ◽  
Second Stage ◽  
Low Visibility ◽  
Recommendation Diversity ◽  
Optimisation Model ◽  
Definition Of ◽  
Improved Methods

Attraction recommendation plays an important role in tourism, such as solving information overload problems and recommending proper attractions to users. Currently, most recommendation methods are dedicated to improving the accuracy of recommendations. However, recommendation methods only focusing on accuracy tend to recommend popular items that are often purchased by users, which results in a lack of diversity and low visibility of non-popular items. Hence, many studies have suggested the importance of recommendation diversity and proposed improved methods, but there is room for improvement. First, the definition of diversity for different items requires consideration for domain characteristics. Second, the existing algorithms for improving diversity sacrifice the accuracy of recommendations. Therefore, the article utilises the topic ‘features of attractions’ to define the calculation method of recommendation diversity. We developed a two-stage optimisation model to enhance recommendation diversity while maintaining the accuracy of recommendations. In the first stage, an optimisation model considering topic diversity is proposed to increase recommendation diversity and generate candidate attractions. In the second stage, we propose a minimisation misclassification cost optimisation model to balance recommendation diversity and accuracy. To assess the performance of the proposed method, experiments are conducted with real-world travel data. The results indicate that the proposed two-stage optimisation model can significantly improve the diversity and accuracy of recommendations.

scholarly journals Two-stage multi-tasking transform framework for large-scale many-objective optimization problems

2021 ◽  
Author(s):  
Lu Chen ◽  
Handing Wang ◽  
Wenping Ma
Keyword(s):  
Large Scale ◽  
Original Problem ◽  
Optimization Problems ◽  
Reference Points ◽  
Optimization Strategy ◽  
Two Stage ◽  
Decision Space ◽  
Second Stage ◽  
Decision Variables ◽  
Objective Space

AbstractReal-world optimization applications in complex systems always contain multiple factors to be optimized, which can be formulated as multi-objective optimization problems. These problems have been solved by many evolutionary algorithms like MOEA/D, NSGA-III, and KnEA. However, when the numbers of decision variables and objectives increase, the computation costs of those mentioned algorithms will be unaffordable. To reduce such high computation cost on large-scale many-objective optimization problems, we proposed a two-stage framework. The first stage of the proposed algorithm combines with a multi-tasking optimization strategy and a bi-directional search strategy, where the original problem is reformulated as a multi-tasking optimization problem in the decision space to enhance the convergence. To improve the diversity, in the second stage, the proposed algorithm applies multi-tasking optimization to a number of sub-problems based on reference points in the objective space. In this paper, to show the effectiveness of the proposed algorithm, we test the algorithm on the DTLZ and LSMOP problems and compare it with existing algorithms, and it outperforms other compared algorithms in most cases and shows disadvantage on both convergence and diversity.

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