Flow Regimes in Bubble Columns with and without Internals: A Review

Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflow regimes established in bubble columns.Some effort is also provided to introduce relevant definitions pertaining to thisfield,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,baffles,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited influence on the global column hydrodynamics.However,they can make the homogeneousflow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenfilled yet and future directions of investigation.

Predicting and delineating soil temperature regimes of China using pedotransfer function

Soil temperature regime(STR)is important for soil classification and land use.Generally,STR is delineated by estimating the mean annual soil temperature at a depth of 50 cm(MAST50)according to the Chinese Soil Taxonomy(CST).However,delineating the STR of China remains a challenge due to the difficulties in accurately estimating MAST50.The objectives of this study were to explore environmental factors that influence the spatial variation of MAST50 and generate an STR map for China.Soil temperature measurements at 40 and 80 cm depth were collected from 386 National Meteorological Stations in China during 1971–2000.The MAST50 was calculated as the average mean annual soil temperature(MAST)from 1971–2000 between 40 and 80 cm depths.In addition,2048 mean annual air temperature(MAAT)measurements from 1971 to 2000 were collected from the National Meteorological Stations across China.A zonal pedotransfer function(PTF)was developed based on the ensemble linear regression kriging model to predict the MAST50 in three topographic steps of China.The results showed that MAAT was the most important variable related to the variation of MAST50.The zonal PTF was evaluated with a 10%validation dataset with a mean absolute error(MAE)of 0.66°C and root mean square error(RMSE)of 0.78°C,which were smaller than the unified model with MAE of 0.83°C and RMSE of 0.96°C,respectively.This study demonstrated that the zonal PTF helped improve the accuracy of the predicted MAST50 map.Based on the prediction results,an STR map across China was generated to provide a consistent scientific base for the improvement and application of CST and land use support.

Influence Mechanism of Curing Regimes on Interfacial Transition Zone of Lightweight Ultra-High Performance Concrete

This study aims to clarify the effects of curing regimes and lightweight aggregate(LWA)on the morphology, width and mechanical properties of the interfacial transition zone(ITZ) of ultra-high performance concrete(UHPC), and provide reference for the selection of lightweight ultra-high performance concrete(L-UHPC) curing regimes and the pre-wetting degree LWA. The results show that, under the three curing regimes(standard curing, steam curing and autoclaved curing), LWA is tightly bound to the matrix without obvious boundaries. ITZ width increases with the water absorption of LWA and decreases with increasing curing temperature. The ITZ microhardness is the highest when water absorption is 3%, and the microhardness value is more stable with the distance from LWA. Steam and autoclaved curing increase ITZ microhardness compared to standard curing. As LWA pre-wetting and curing temperatures increase, the degree of hydration at the ITZ increases, generating high-density CSH(HD CSH) and ultra-high-density CSH(UHD CSH), and reducing unhydrated particles in ITZ. ITZ micro-mechanical properties are optimized due to hydration products being denser.

Controlled transition to different proton acceleration regimes:Near-critical-density plasmas driven by circularly polarized few-cycle pulses

A controlled transition between two different ion acceleration mechanisms would pave the way to achieving different ion energies and spectral features within the same experimental set up,depending on the region of operation.Based on numerical simulations conducted over a wide range of experimentally achievable parameter space,reported here is a comprehensive investigation of the different facets of ion acceleration by relativistically intense circularly polarized laser pulses interacting with thin near-critical-density plasma targets.The results show that the plasma thickness,exponential density gradient,and laser frequency chirp can be controlled to switch the interaction from the transparent operating regime to the opaque one,thereby enabling the choice of a Maxwellian-like ion energy distribution with a cutoff energy in the relativistically transparent regime or a quasi-monoenergetic spectrum in the opaque regime.Next,it is established that a multispecies target configuration can be used effectively for optimal generation of quasi-monoenergetic ion bunches of a desired species.Finally,the feasibility is demonstrated for generating monoenergetic proton beams with energy peak atℰ≈20–40 MeV and a narrow energy spread ofΔℰ/ℰ≈18%–28.6%confined within a divergence angle of∼175 mrad at a reasonable laser peak intensity of I0≃5.4×10^(20)W/cm^(2).

The Ocean-Atmosphere Coupled Regimes and East Asian Winter Monsoon (EAWM) Activity

In this paper, ocean-atmosphere coupled regimes are identified on the basis of SVD analysis, cluster analysis and composite analysis. The coupled regimes in cold seasons are identified as the clusters of the ocean-atmosphere coupled states in a low dimensional phase space spanned by the first four SVD modes. Three coupled regimes are found. The first two coupled regimes reflect the ENSO episodes and the accompanying PNA patterns. The third regime, i.e., EAWM regime, is characterized by the strong EAWM activity and the specific SST anomaly. The composite analysis gives further evidences to the identification of EAWM regime and also demonstrates the dynamical process of its formation. The anomaly pattern of the tropical Pacific SSTA in the strong EAWM year differs significantly from that of the La Nina year.

Markov repairable systems with stochastic regimes switching

Compared with the classical Markov repairable system, the Markov repairable system with stochastic regimes switching introduced in the paper provides a more realistic description of the practical system. The system can be used to model the dynamics of a repairable system whose performance regimes switch according to the external conditions. For example, to satisfy the demand variation that is typical for the power and communication systems and reduce the cost, these systems usually adjust their operating regimes. The transition rate matrices under distinct operating regimes are assumed to be different and the sojourn times in distinct regimes are governed by a finite state Markov chain. By using the theory of Markov process, Ion channel theory, and Laplace transforms, the up time of the system are studied. A numerical example is given to illustrate the obtained results. The effect of sojourn times in distinct regimes on the availability and the up time are also discussed in the numerical example.

The effects of rainfall regimes and rainfall characteristics on peak discharge in a small debris flow-prone catchment

Peak discharge plays an important role in triggering channelized debris flows.The rainfall regimes and rainfall characteristics have been demonstrated to have important influences on peak discharge.In order to explore the relationship between rainfall regimes and peak discharge,a measuring system was placed at the outlet of a small,debris flow-prone catchment.The facility consisted of an approximately rectangular stilling basin,ending with a sharp-crested weir.Six runoff events were recorded which provided a unique opportunity for characterizing the hydrological response of the debris flow-prone catchment.Then,a rainfall–runoff model was tested against the flow discharge measurements to have a deep understanding of hydrological response.Based on the calibrated rainfall-runoff model,twelve different artificially set rainfall patterns were regarded as the input parameters to investigate the effect of rainfall regimes on peak discharge.The results show that the rainfall patterns have a significant effect on peak discharge.The rainfall regimes which have higher peak rainfall intensity and peak rainfall point occur at the later part of rainfall process are easy to generate larger peak discharge in the condition of the same cumulative rainfall and duration.Then,in order to explore the relationship between rainfall characteristics and peak discharge under different cumulative precipitation and different duration,167 measured rainfall events were also collected.On the basis of rainfall depth,rainfall duration,and maximum hourly intensity,all the rainfall events were classified into four categories by using K-mean clustering.Rainfall regime 1 was composed of rainfall events with a moderate mean P(precipitation),a moderate D(duration),and a moderate I60(maximum hourly intensity).Rainfall regime 2 was the group of rainfall events with a high mean P,long D.Rainfall regime 3,however,had a low P and a long D.The characteristic of Rainfall regime 4 was high I60 and short duration with large P.The results show that the rainfall regime 2 and 4 are easier to generate peak discharge as the rainfall intensity plays an important role in generating peak discharge.The results in this study have implications for improving peak discharge prediction accuracy in debris flow gully.

Hydration Products of Cement-silica Fume-quartz Powder Mixture under Different Curing Regimes

Composition, morphology, and structure of hydration products in hardened pastes of three kinds of blended cement（cement-silica fume, cement-quartz powder and cement-silica fume-quartz powder） hydrated under different curing regimes（standard curing, 90 ℃ steam curing, 200 ℃ and 250 ℃ autoclave curing） were investigated by X-ray diffraction and field emission scanning electron microscope equipped with EDAX system. Results showed that the main hydration products in three kinds of hardened pastes under standard curing condition are all C-S-H gels, CH, and AFt. Under 90 ℃ steam curing condition, the main hydration products of cement-silica fume and cement-silica fume-quartz powder are C-S-H gels, whereas those of cement-quartz powder are C-S-H and CH. Under 200 or 250 ℃ autoclave curing condition, no obvious crystallized CH phase is found in hardened pastes of three kinds of blended cement, and C-S-H gels are transformed into one or more crystalline phases such as tobermorite, jennite, and xonotlite. The chemical composition and morphology of these crystalline phases depend on the composition of mixture and autoclave temperature.

Modeling the Parking Pricing of Multiple Parking Facilities under Different Operation Regimes

To explore the parking pricing of multiple parking facilities, this paper proposes a bi-level programming model, in which the interactions between parking operators and travelers are explicitly considered. The upper-level sub-model simulates the price decision-making behaviors of the parking operators whose objectives may vary under different operation regimes, such as monopoly market, oligopoly competition, and social optimum. The lower level represents a network equilibrium model that simulates how travelers choose modes, routes, and parking facilities. The proposed model is solved by a sensitivity based algorithm, and applied to a numerical experiment, in which three types of parking facilities are studied, i.e., the off-road parking lot, the curb parking lot, and the parking-and-ride (P&R) facility. The results show in oligopoly market that the level of parking price reaches the lowest point, nonetheless the social welfare decreases to the lowest simultaneously;and the share of P&R mode goes to the highest value, however the total network costs rise also to the highest. While the monopoly market and the social optimum regimes result in solutions of which P&R facilities suffer negative profits and have to be subsidized.

Evaluating the Impact of Different Tillage Regimes and Nitrogen Levels on Yield and Yield Components of Maize (Zea mays L.)

A field study to evaluate the impact of different tillage regimes and nitrogen levels on yield and yield components of maize (Zea mays L.), was conducted during autumn 2014 at Students Farm, Department of Agronomy, University of Agriculture, Faisalabad. The experiment was laid out in RCBD (Randomized Complete Block Design), with split plot arrangement having three replications. The experiment was comprised of three tillage regimes (Minimum, Conventional and Deep) and three nitrogen levels viz: 100, 200 and 300 kg•ha-1. Urea was used as a source of nitrogen, sulphate of potash as a source of potassium and triple super phosphate as a source of phosphorous. The amount of phosphorous and potash was constant in all the treatments i.e. 125 kg•ha-1 and 100 kg•ha-1 respectively. Results of present study are summarized as yield parameters are significantly affected by different nitrogen levels and tillage regimes. Maximum number of plants at harvest (7.93), number of grain rows per cob (17.70), number of grains per row (34.31), number of grains per cob (678.58), and cob weight (187.50 g) were observed in deep tillage at 200 kg•ha-1 nitrogen application. 1000-grain weight (275.52 g), biological yield (15.66 t•ha-1), grain yield (6.16 t•ha-1) and dried stalk yield (9.91 t•ha-1) were observed maximum in deep tillage at 200 kg•ha-1 nitrogen application. Harvest index significantly affected by tillage regimes and maximum harvest index (39.58%) were recorded in deep tillage which was statistically at par with conventional tillage (38.83%). It was concluded that higher grain yield of maize can be obtained by deep tillage with the application of 200 kg•ha-1 nitrogen application under the prevailing conditions of Faisalabad.

Numerical Study of the Transition Between Reentrant Jet and Twin Vortex Flow Regimes in Ventilated Cavitation

Contrary to natural cavitation,ventilated cavitation is controllable and is not harmful.It is particularly used to reduce the drag of the hydraulic vehicles.The ventilated cavitation is characterized by various gas regimes.The mechanisms of ventilated cavitation are investigated in the present work with CFD based on a 2D solver.The attention is especially focused on the transition between the reentrant jet and twin vortex regimes.The results confirmthat the product of ventilated cavitation number and Froude number is lower than 1(σcFr<1)in the twin vortex regime,while it is higher than 1(σcFr>1)in the reentrant jet regime,as reported in the literature.Further analysis shows that ventilated cavitation is significantly influenced by the natural cavitation number.

Dissipative dynamics of an entangled three-qubit system via non-Hermitian Hamiltonian: Its correspondence with Markovian and non-Markovian regimes

We investigate an entangled three-qubit system in which only one of the qubits experiences the decoherence effect by considering a non-Hermitian Hamiltonian,while the other two qubits are isolated,i.e.,do not interact with environment,directly.Then,the time evolution of the density matrix(for the pure as well as mixed initial density matrix)and the corresponding reduced density matrices are obtained,by which we are able to utilize the dissipative non-Hermitian Hamiltonian model with Markovian and non-Markovian regimes via adjusting the strange of the non-Hermitian term of the total Hamiltonian of the under-considered system.

Switching Regimes in Economics: The Contraction Mapping and the &omega;-Limit Set

This paper considers a dynamical system defined by a set of ordinary autonomous differential equations with discontinuous right-hand side. Such systems typically appear in economic modelling where there are two or more regimes with a switching between them. Switching between regimes may be a consequence of market forces or deliberately forced in form of policy implementation. Stiefenhofer and Giesl [1] introduce such a model. The purpose of this paper is to show that a metric function defined between two adjacent trajectories contracts in forward time leading to exponentially asymptotically stability of (non)smooth periodic orbits. Hence, we define a local contraction function and distribute it over the smooth and nonsmooth parts of the periodic orbits. The paper shows exponentially asymptotical stability of a periodic orbit using a contraction property of the distance function between two adjacent nonsmooth trajectories over the entire periodic orbit. Moreover it is shown that the ω-limit set of the (non)smooth periodic orbit for two adjacent initial conditions is the same.

Seed Germination and Effects of Three Watering Regimes on the Growth of <i>Dialium guineense</i>(Wild) Seedlings

The effectiveness of three pre-germination treatments in breaking dormancy of the seeds of Dialum guineense and effects of three watering regimes on the growth performance of the seedlings were investigated. The pre-germination treatments were: soaking in hot water for 10 seconds and cooling down in cold water (T1), soaking in cold water for 24 hours (T2), soaking in running water for 48 hours (T3) and control (T4), while watering regimes include: watering once daily in the morning (W1), watering once every two days in the morning (W2) and watering once every three days in the morning (W3). The results showed that germination occurred first at 5 days after sowing (5 DAS) among the seeds soaked in cold water for 24 hours before sowing (T2), while the untreated seeds (control) took the longest period of 12 days before germination occurred. T1 had the highest germination value of 49.6% while T3 had the least of 31.2%. The effects of watering regimes were found to be significantly different on stem-collar diameter, leaf area and total dry weight (P < 0.05). The least significant difference (LSD) test showed that W2 and W3 supported the best growth performance. It is concluded from the results that T2 should be adopted for breaking the dormancy of Dialium guineense seeds and watering interval of three days would not dispose the seedlings to water-stress.

Growth and Yield of Sesame (<i>Sesamum indicum</i>L.) under the Influence of Planting Geometry and Irrigation Regimes

A field study to evaluate the “growth and yield of sesame (Sesamum indicum L.) under the influence of planting geometry and irrigation regimes” was carried out at Oilseeds Section, Agriculture Research Institute, Tandojam located at (25°25'60"N, 68°31'60"E) during Kharif 2013. The experiment was laid out in a three replicated randomized complete block design (RCBD) factorial, having net plot size 3 × 3 m (9 m2). The treatments comprised three planting geometry (30 × 20 cm, 45 × 15 cm and 60 × 10 cm) and three irrigation regimes (2 irrigations at 20 and 40 DAS, 3 irrigations at 20, 40 and 60 DAS and 4 irrigations at 20, 40, 60 and 80 DAS). The analysis of variance showed that all the planting geometry and irrigation regimes significantly (P -1 (15.67), capsules plant-1 (38.00), seeds capsule-1 (51.44), seed weight plant-1 (31.89 g), seed index (2.83 g), biological yield (2301.23 kg·ha-1), seed yield (742.33 kg·ha-1) and harvest index (30.44%), followed by planting geometry of 60 × 10 cm in all the parameters. However, minimum growth and yield traits of sesame were recorded under planting geometry of 30 × 20 cm. Moreover, plant height was maximum (99.89 cm) under planting geometry of 30 × 20 cm. Among irrigation regimes, four irrigations (20, 40, 60 and 80 DAS) recorded maximum plant height (103.33 cm), branches plant-1 (16.44), capsules plant-1 (41.22), seeds capsule-1 (54.56), seed weight plant-1 (33.22 g), seed index (2.92 g), biological yield (2321.21 kg·ha-1), seed yield (748.78 kg·ha-1) and harvest index (31.00%), followed by three irrigations (20, 40 and 60 DAS) almost in all the traits. However, minimum growth and yield traits of sesame were recorded when crop was applied two irrigations (20 and 40 DAS). In case of interactive effects, the interaction of planting geometry of 45 × 15 cm × four irrigations (20, 40, 60 and 80 DAS) resulted in maximum attributes, particularly seed yield (765.00 kg·ha-1), whereas minimum traits were noted in the interaction of planting geometry of 30 × 20 cm × two irrigations (20 and 40 DAS). Furthermore, the results of four and three irrigations had non-significant differences with each other means not sharing the same letter differ significantly at 0.05 probability level. Hence, it is concluded that interaction of 45 × 15 cm planting geometry and three irrigations (20, 40 and 60 DAS) is conducive to produce maximum seed yield (kg·ha-1) of sesame.

GLOBAL WARMING EFFECTS ON THE HANJIANG RIVER HYDROLOGICAL REGIMES

The paper, based on a semi-conceptual hydrological model, analysed global warming effects on the Hanjiang River hydrological regimes and water resources, including soil moisture, evaporation, runoff and the transferable water quantity from the Danjiangkou Reservoir according to Middle Route of China's South-to-North Water Transfer Project.

Soil Microbial Biomass of Pea (<i>Pisium sativum</i>cv. Little Marvel) in Response to Three Atmospheric Air Regimes at Al Baha Region, KSA

This study was conducted to determine the effect of atmospheric air on soil health in pots involving the growth of pea under two soil moisture regimes. Twelve pots were treated with three air quality treatments of urban, suburban and rural sites. In situ soil respiration increased under urban and suburban while it decreased little under rural site atmospheric conditions. These data support the relationships between the number of microorganisms in soils and carbon dioxide fluxes. Microbial biomass, metabolic quotient and crop yields or biomass were found most sensitive indicators of soil quality, which significantly varied in response to air quality and soil moisture regimes. The soil microbial biomass, metabolic quotient, and basal respiration were the most practical quality index variables;however, when using only a single predicator, microbial biomass was the most sensitive indicator of the soil quality.

Altered Fire Regimes and the Persistence of Quaking Aspen in the Rocky Mountains: A Literature Review

The persistence of quaking aspen (Populus tremuloides Michx.) is of significant importance to land managers in the Rocky Mountain region. Fire suppression in the past century has been implicated as a mechanism influencing aspen population dynamics, as aspen are generally considered an early seral disturbance adapted species. The heterogeneity of aspen community assemblages and fire regimes makes it difficult to discern what the result of fire suppression has been at large spatial and temporal scales. Decision makers should investigate the questions at hand at the stand level in their study location to best determine the mechanisms at play, as well as consider future potential changes to the system.

Effect of Water Regimes on Dietary Fiber, Polyphenols and Antioxidant Capacity of Black and Pinto Beans

Beans are rich in dietary fiber and polyphenols;however, growing conditions may affect the occurrence of these components. The effect of irrigation and rain fed conditions on dietary fiber, indigestible fraction, polyphenols and antioxidant capacity of Black 8025 and Pinto Durango bean cultivars grown in Mexico have been determined. Total dietary fiber decreased in beans grown under rain fed conditions compared to those grown under irrigation. The water regimes had an effect on the total indigestible fraction for Black 8025 bean. The extractable polyphenols were affected by the water regimes, while the antioxidant capacity of extractable and non-extractable polyphenols was dependent on the bean variety. Cooking the beans altered the extractable and non-extractable polyphenols and the antioxidant capacity. Also, the antioxidant properties and some extend, the digestibility of non-digestible carbohydrates of beans were affected by water regimes. This information could be taken into account for dry bean breeding programs to improve the nutritional quality of beans.

Fukushima Plutonium Effect and Blow-Up Regimes in Neutron-Multiplying Media

It is shown that the capture and fission cross-sections of 238U and 239Pu increase with temperature within 1000 K - 3000 K range, in contrast to those of 235U, that under certain conditions may lead to the so-called blow-up modes, stimulating the anomalous neutron flux and nuclear fuel temperature growth. Some features of the blow-up regimes in neutronmultiplying media are discussed.