Emerging trends in expansive soil stabilisation: A review

Expansive soils are problematic due to the performances of their clay mineral constituent, which makes them exhibit the shrink-swell characteristics. The shrink-swell behaviours make expansive soils inappropriate for direct engineering application in their natural form. In an attempt to make them more feasible for construction purposes, numerous materials and techniques have been used to stabilise the soil. In this study, the additives and techniques applied for stabilising expansive soils will be focused on,with respect to their efficiency in improving the engineering properties of the soils. Then we discussed the microstructural interaction, chemical process, economic implication, nanotechnology application, as well as waste reuse and sustainability. Some issues regarding the effective application of the emerging trends in expansive soil stabilisation were presented with three categories, namely geoenvironmental,standardisation and optimisation issues. Techniques like predictive modelling and exploring methods such as reliability-based design optimisation, response surface methodology, dimensional analysis, and artificial intelligence technology were also proposed in order to ensure that expansive soil stabilisation is efficient.

In-situ stabilisation followed by ex-situ composting for treatment and disposal of heavy metals polluted sediments

An innovative in-situ stabilisation treatment followed by ex-situ sediment composting was tested for its ability to treat and dispose of heavy-metal-polluted sediments in a river near the Chinese Pearl Delta. First, polluted sediments were treated in-situ to stabilise the heavy metals. Then the treated sediments were dredged, dewatered and sent for high temperature aerobic composting （HTAC） treatment. Finally, the compost products were used as a fertiliser for fiver bank plants. The stabilisation efficiency of heavy metals during the process was investigated and the results are as follows： （1） using in-situ stabilisation, the extraction concentrations of Cu, Zn and Pb were reduced by 65.0%, 82.2% and 90.0%, respectively, which are much lower than the national standard given in the Identification Standard for Hazardous Waste （GB5085.3-1996）; （2） chemical fraction analysis showed that heavy metals were further stabilized during the HTAC treatment; （3） the concentrations of Cu, Zn and Pb in rainwater leachate through the river bank met the level of class V in the Environmental Quality Standards for Surface Water in China （GB3838-2002）. Therefore, using this new process, the toxicities of heavy metals in sediments were reduced markedly.

Incorporation of a nanotechnology-based additive in cementitious products for clay stabilisation

The mechanical performances and water retention characteristics of clays,stabilised by partial substitution of cement with by-products and inclusion of a nanotechnology-based additive called RoadCem(RC),are studied in this research.The unconfined compression tests and one-dimensional oedometer swelling were performed after 7 d of curing to understand the influence of addition of 1%of RC material in the stabilised soils with the cement partially replaced by 49%,59%and 69%of ground granulated blast furnace slag(GBBS)or pulverised fuel ash(PFA).The moisture retention capacity of the stabilised clays was also explored using the soil-water retention curve(SWRC)from the measured suctions.Results confirmed an obvious effect of the use of RC with the obtained strength and swell properties of the stabilised clays suitable for road application at 50%replacement of cement.This outcome is associated with the in-depth and penetrating hydration of the cementitious materials by the RC and water which results in the production of needle-like matrix with interlocking filaments e a phenomenon referred to as the‘wrapping’effect.On the other hand,the SWRC used to describe the water holding capacity and corresponding swell mechanism of clays stabilised by a proportion of RC showed a satisfactory response.The moisture retention of the RC-modified clays was initially higher but reduced subsequently as the saturation level increased with decreasing suction.This phenomenon confirmed that clays stabilised by including the RC are water-proof in nature,thus ensuring reduced porosity and suction even at reduced water content.Overall,the stabilised clays with the combination of cement,GGBS and RC showed a better performance compared to those with the PFA included.

Laboratory-scale model of carbon dioxide deposition for soilstabilisation

Olivine sand is a natural mineral,which,when added to soil,can improve the soil’s mechanical properties while also sequester carbon dioxide(CO2)from the surrounding environment.The originality of this paper stems from the novel two-stage approach.In the first stage,natural carbonation of olivine and carbonation of olivine treated soil under different CO2pressures and times were investigated.In this stage,the unconfined compression test was used as a tool to evaluate the strength performance.In the second stage,details of the installation and performance of carbonated olivine columns using a laboratory-scale model were investigated.In this respect,olivine was mixed with the natural soil using the auger and the columns were then carbonated with gaseous CO2.The unconfined compressive strengths of soil in the first stage increased by up to 120% compared to those of the natural untreated soil.The strength development was found to be proportional to the CO2pressure and carbonation period.Microstructural analyses indicated the presence of magnesite on the surface of carbonated olivinetreated soil,demonstrating that modified physical properties provided a stronger and stiffer matrix.The performance of the carbonated olivine-soil columns,in terms of ultimate bearing capacity,showed that the carbonation procedure occurred rapidly and yielded a bearing capacity value of 120 k Pa.Results of this study are of significance to the construction industry as the feasibility of carbonated olivine for strengthening and stabilizing soil is validated.Its applicability lies in a range of different geotechnical applications whilst also mitigates the global warming through the sequestration of CO2.

Performance Evaluation of Waste Stabilisation Ponds

Waste stabilisation pond system has been used more especially in developing countries for sewage treatment. The objective of this study was to investigate the hydraulic and performance efficiency of Palapye waste stabilisation ponds. The hydraulic efficiency was evaluated through drogue, pond geometry and sludge accumulation assessment. The performance efficiency was evaluated through periodic sampling and analysis of physiochemical and bacteriological parameters of individual units and of the system as a whole. Except for the maturation ponds, the depth of the anaerobic pond had reduced from 4 m to 0.45 m, for facultative ponds from 2.0 m to a range of 0.52 m - 0.91 m. The design hydraulic retention time of the system had reduced from 20 days to 7.1 days. The concentration of some physiochemical parameters in the effluent was 305 mg·L-1, 277 Nephelometric Turbidity Units (NTU), 204 mg·L-1, 156 mg·L-1, 110 mg·L-1, and 15 mg·L-1 being total suspended solids, turbidity, nitrates, chemical oxygen demand, biochemical oxygen demand and phosphate respectively. These values were more than the standard limits of the country. Effluent total coliforms concentration was 3.6 log units and within the threshold of 4.3 log units, faecal coliforms concentration was 3.5 log units, slightly higher than the threshold of 3 log units. Though Escherichia coli have no limits for discharge into other environments, the concentration in the effluent was reasonable at 2.5 log units and also within irrigation limit of 3 log counts. Palapye wastewater treatment system hydraulic efficiency is lower than the design criterion. The system was overall poor in physiochemical parameters removal but better in bacteriological removal.

Stabilisation of Pb in Pb Smelting Slag-Contaminated Soil by Compost-Modified Biochars and Their Effects on Maize Plant Growth

Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.

Models to predict sunlight-induced photodegradation rates of contaminants in wastewater stabilisation ponds and clarifiers

Two kinetic models were established for conservative estimates of photodegradation rates of contaminants under sunlight irradiation,in particular for wastewater stabilisation ponds and clarifiers in conventional wastewater treatment plants.These two models were designated for(1)contaminants with high photolytic rates or high photolytic quantum yields,whose photodegradation is unlikely to be enhanced by aquatic photosensitisers;and(2)contaminants withstanding direct photolysis in sunlit waters but subjected to indirect photolysis.The effortlessly intelligible prediction procedure involves sampling and analysis of real water samples,simulated solar experiments in the laboratory,and transfer of the laboratory results to realise water treatment using the prediction models.Although similar models have been widely used for laboratory studies,this paper provides a preliminary example of translating laboratory results to the photochemical fate of contaminants in real waters.

Effects of Lateral Variation in Vegetation and Basin ‘Dome' Shape on Tropical Lowland Peat Stabilisation in the Kota Samarahan-Asajaya Area, West Sarawak, Malaysia

Field surveys indicate lateral variation in peat humification levels （von Post） in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of tropical lowland peat domes.Cement-peat stabilisation can be enhanced by adding mineral soil fillers （silt,clays and fine sands） obtained from Quaternary floodplain deposits and residual soil （weathered schist）.The unconfined compressive strength （UCS） of the stabilised cement-mineral soil fifler-peat mix increases with the increased addition of selected mineral soil filler.Lateral variation in the stabilised peat strength （UCS） in the top 0 to 0.5 m layer was found from the margin towards the centre of the tropical lowland peat dome.The variations in the UCS of stabilised tropical lowland peats along a gradient from the periphery towards the centre of the peat dome are most likely caused by a combination of factors due to variations in the mineral soil or ash content of the peat and horizontal zonation or lateral variation in the dominant species of the plant assemblages （due to successive vegetation zonation of the peat swamp forest from the periphery towards the centre of the tropical lowland peat dome）.

SPH Particle Collisions for the Reduction of Particle Clustering, Interface Stabilisation and Wall Modelling

The pair-wise forces in the SPH momentum equation guarantee the conservation of momentum, but they cannot prevent particle clustering and wall penetration. Particle clustering may occur for several reasons. A fundamental issue is the tensile instability, which is caused by negative numerical pressures. Clustering may also occur due to certain properties of the kernel gradient. Discontinuities in the pressure and its gradient, due to surface tension and gravity, may cause particle instabilities near the interface between two fluids. Wall penetration is also a form of particle clustering. In this paper the particle collision concept is introduced to suppress particle clustering. Here, the use of kinematic conditions (motion) rather than dynamic conditions (forces) is explored. These kinematic conditions are obtained from kinetic collision theory. Conservation of momentum is maintained, and under elastic conditions conservation of energy as well. The particle collision model only becomes active when needed. It may be seen as a particle shifting method, in the sense that the velocities are changed, and as a consequence of that the particle positions change. It is demonstrated in several case studies that the particle collision model allows for realistic (low) viscosities. It was also found to stabilise the interface between two fluids up to high, realistic density ratios (1000:1) in typical liquid-gas applications. As such it can be used as a multi-fluid model. The concept allows for real wave speed ratios (and far beyond), which, as well as real viscosities, are essential in the modelling of heat transfer applications. The collisions with walls allow for no-slip conditions at real viscosities while wall penetration is suppressed. In summary, the particle collision model makes SPH more robust for engineering.

Stability and stabilisation of Markovian jump systems under fast switching: an averaging approach

ABSTRACTThis paper addresses the problems of stability and stabilisation of Markovian jump systems(MJSs) with fast switching. First, a novel model by applying an averaging approach to the fastswitching is proposed. Then, a new method for constructing an auxiliary system is given to makethe stability analysis. It is proved that the stability of the originally fast switching MJS couldbe guaranteed by an MJS with an average switching, if the fast switching achieves its averageapproximation sufficiently fast. Based on the proposed results, some extensions about generally stabilising controllers are considered, where the fault-tolerant situation is involved too.All the conditions are presented in terms of LMIs. Finally, two numerical examples are used todemonstrate the effectiveness and superiority of the method.

Prescribed-time stabilisation control of differential driven automated guided vehicle

The position control problem of differential-driven automated guided vehicles(AGVs)based on the prescribed-time control method is studied.First,an innovative orientation error function is proposed by an auxiliary arcsine function about the orientation angle.Thus,the problem of position control of AGV is transformed into the stabilisation control of the kinematic system.Second,by introducing a reserved time parameter and a smooth switching function,a novel time-varying scaling function is proposed.This novel scaling function avoids the risk of infinite gain in the conventional prescribed-time control method while ensuring the smoothness of control laws.Then,an improved velocity constraint function is proposed using the Gaussian function.Compared with the existing constraint function,the proposed method not only has more smoothness but also solves the balance point errors caused by the large AGV orientation errors.The presented method ensures that the AGV reaches the target position in a prescribed time.Hence,the upper bound of the AGV system state can be determined by adjusting parameters.Matlab simulation results show that the proposed controller can effectively make the AGV system state satisfy the prescribed bound.

Quadratic stabilisation of switched affine systems

Minqing Xiao received the Ph.D.degree from Chongqing University,Chongqing,China,in 2008.He is currently a Professor with the College of Mathematics and Informatics,Fujian Normal University,Fuzhou,China.His current research interests include robust control/filter theory,delta operator systems,networked control systems,and switched systems;Guisheng Zhai received his B.S.degree from Fudan University,China,in 1988,and he received his M.E.and Ph.D.degrees,both in system science,from Kobe University,Japan,in 1993 and 1996,respectively.After two years of industrial experience,Dr.Zhai moved to Wakayama University,Japan,in 1998,and then to Osaka Prefecture University,Japan,in 2004.He held visiting professor positions at University of Notre Dame from August 2001 to July 2002,and at Purdue University from March 2016 through February 2017.In April 2010,he joined the faculty board of Shibaura Institute of Technology,Japan,where he currently is a full Professor of Mathematical Sciences.His research interests include large scale and decentralised control systems,robust control,switched systems and switching control,networked control and multi-agent systems,neural networks and signal processing,etc.Dr.Zhai is on the editorial board of several academic journals including IET Control Theory&Applications,International Journal of Applied Mathematics and Computer Science,Journal of Control and Decision,and Frontiers of Mechanical Engineering.He is a Senior Member of IEEE,a member of ISCIE,SICE,JSST and JSME.

Chinese Macroeconomic Stabilisation and Reform:A Briefing Note

While reform of the Chinese public and external sectors has promoted growth, it has alsoled to increasing macroeconomic volatility. Such volatility has largely been due to Chinasde facto administrative and fiscal decentralisation and its de jure attempts at reassertingcentral control through fiscal and commercial regulation. Section II will discuss somereasons for Chinas rapid economic growth and discuss the macro-level influences whichcaused output and inflation instability in the period 1979-1996. Section III will discuss theeffects of public sector reform on output and prices. Section IV will explore trade reformseffects on output and prices. The conclusion will discuss implications for stabilisation where stabilisation is taken to comprise economic policies aimed at reducing inflationwhile promoting long-term output growth.

Strong and weak output stabilisation for distributed bilinear systems

This paper is concerned with the output stabilisation for a class of distributed bilinear system evolving in a spatial domain.We give sufficient conditions for strong and weak output stabilisation.Also,the output stabilisation is discussed using a minimisation problem.Examples and simulations are given.

Robust adaptive passification and global stabilisation for uncertain switched nonlinear systems

In this paper,we focus on the problems of feedback passification and global stabilisation for a class of uncertain switched non-linear systems with parameter uncertainties and structural uncertainties.A state-dependent switching law and adaptive feedback controllers are designed to render the resulting closed-loop systems passive.The corresponding passivity-based adaptive stabilisation problems for these systems are solved.Finally,a numerical example is presented to illustrate the effectiveness of our method.

Sternoclavicular joint dislocation and its management: A review of the literature

Dislocations of the sternoclavicular joint(SCJ) occur with relative infrequency and can be classified into anterior and posterior dislocation, with the former being more common. The SCJ is inherently unstable due to its lack of articular contact and therefore relies on stability from surrounding ligamentous structures, such as the costoclavicular, interclavicular and capsular ligaments. The posterior capsule has been shown in several studies to be the most important structure in determining stability irrespective of the direction of injury. Posterior dislocation of the SCJ can be associated with life threatening complications such as neurovascular, tracheal and oesophageal injuries. Due to the high mortality associated with such complications, these injuries need to be recognised acutely and managed promptly. Investigations such as x-ray imaging are poor at delineating anatomy at the level of the mediastinum and therefore CT imaging has become the investigation of choice. Due to its rarity, the current guidance on how to manage acute and chronic dislocations is debatable. This analysis of historical and recent literature aims to determine guidance on current thinking regarding SCJ instability, including the use of the Stanmore triangle. The described methods of reduction for both anterior and posterior dislocations and the various surgical reconstructive techniques are also discussed.

Diagnosing syndesmotic instability in ankle fractures

The precise diagnosis of distal tibiofibular syndesmotic ligament injury is challenging and a distinction should be made between syndesmotic ligament disruption and real syndesmotic instability.This article summarizes the available evidence in the light of the author’s opinion.Pre-operative radiographic assessment,standard radiographs,computed tomography scanning and magnetic resonance imaging are of limited value in detecting syndesmotic instability in acute ankle fractures but can be helpful in planning.Intra-operative stress testing,in the sagittal,coronal or exorotation direction,is more reliable in the diagnosis of syndesmotic instability of rotational ankle fractures.The Hook or Cotton test is more reliable than the exorotation stress test.The lateral view is more reliable than the AP mortise view because of the larger displacement in this direction.When the Hook test is used the force should be applied in the sagittal direction.A force of 100 N applied to the fibula seems to be appropriate.In the case of an unstable joint requiring syndesmotic stabilisation,the tibiofibular clear space would exceed 5 mm on the lateral stress test.When the surgeon is able to perform an ankle arthroscopy this technique is useful to detect syndesmotic injury and can guide anatomic reduction of the syndesmosis.Many guidelines formulated in this article are based on biomechanical and cadaveric studies and clinical correlation has to be established.

Bronchodilatory and mast cell stabilising activity of Cressa cretica L.:Evaluation through in vivo and in vitro experimental models

Objective:To evaluate the effect of ethylacetate fraction(Fr-Et) and methanolic fraction(FrMe) obtained from Cressa cretica L.(C.crelica) L on experimental models for bronchodilatory activity and mast cell stabilising activity.Methods:The effect of Fr-Et and Fr-Me were studied on acetylcholine and histamine aerosol-induced broncospasm using guinea pigs as experimental animals.Also,the effects of these fractions were evaluated on the isolated guinea pig tracheal preparations.Besides this mast cell degranulation effect was assessed using egg albumin and compound 48/80 on rat peritoneal mast cells.Results:Significant increase in nreconvulsion time was observed due to pretrealment with the fractions when guinea pigs were exposed to histamine and acetylcholine aerosol.Fr-Et and Fr-Me significantly increased the preconvulsion in a dose depended manner that suggestive of bronchodilating activity.Fr-Et and Fr-Me exhibited a significant concentration dependant relaxant effect on guinea pig trachea pre-contracted with CCh,K^+ and histamine.The results revealed that Fr-Et to be more potent than Fr-Me in relaxing histamine and K^+ and calcium induced contraction than CCh induced conlractions.Studies on the fractions in protecting mast cell degranulation,which were elicited by the egg albumin as well as synthetic compound 48/80 revealed both the fractions significantly protect the mast cell degranulation,which release mediators such as histamine and proinflammatory cytokines through various stimuli in a dose depended manner.Conclusions:Thus our study established the bronchodilator activity,and mast cell stabilizing activity which are important mediators that provoke or sustain in asthma.

Influence of Impurities of Zircon Sand on the Microstructure of Fused Zirconia Grains for Continuous Casting of Steel Refractories

Certain impurities of zircon sands, especially alumina, titania, calcia and yttria cannot be completely re- moved in the production of fused zirconia and may have an influence on the corrosion resistance and other product properties of refractories for continuous casting of steel. In this paper, we present our findings on how impurities in raw materials end up in different stabilised zirconia refractory grains, in particular calcia-, magnesia- and yttria-stabilised zirconia. The microstructure （and phase composition） is affected by both the raw materials and the fusion conditions （furnace type and cooling technology）.

Monitoring of Anthocyanins and Colour in Electrochemically Processed <i>Hibiscus sabdariffa</i>Juice

The vital role of anthocyanins in Hibiscus sabdariffa L. is now known to most consumers. The richness of anthocyanins in antioxidants, vitamin C, minerals, etc., provides Hibiscus juice with proven nutritional qualities. The health requirements of recent years have made food products with added preservatives or processed at high temperatures less popular, thus explaining the new orientations towards innovative and interdisciplinary technologies. Anthocyanins from Hibiscus sabdariffa L. are, however, sensitive to degradation factors such as temperature, light, enzymes and also oxygen. The instability of anthocyanins has long been a subject of research using classic techniques such as heat treatment, the results of which are often limited by the rapid degradation and above all the destruction of the nutritional and organoleptic qualities of the product. Oxygen dissolved in juices is so far treated by bubbling with an inert gas or by adding other molecules such as preservatives which can cause a lot of health damage. The electrochemical approach is a new stabilisation technique that reduces the dissolved oxygen in the juice, cold and without the addition of other molecules. The electrolysis of Hibiscus juice was carried out by noble electrodes (Platinum and Stainless Steel) with a well-characterised Time/Potential or Time/Intensity couple. The electroreduced samples and the control were then stored at 4°C, 25°C and 37°C for more than 6 months. Monitoring of anthocyanins in the first month, of the samples and the control, showed a significant difference of 10% between the electroreduced extract and the untreated control at 37°C, which had previously been problematic for the heat treatment and even for the other membrane techniques. Oxygen reduction on the platinum electrode/ECS allowed the retention of more than 10% of anthocyanins after 4 weeks of storage at 25°C and 37°C. At 4°C, a significant difference of 5% between the electro-reduced Hibiscus juice and the control was maintained until the fifth month of storage with the 1/5 ratio (calyx/water). Non-significant losses in anthocyanin (10 mg/l), for the juice with reduced dissolved oxygen, were noted for the 1/5 and 1/15 ratios during the first month of storage at 4°C against 24 mg/l of significant losses for the 1/20 ratio. However, the untreated control showed significant losses for the ratios 1/20, 1/15 and 1/5. Oxygen dissolved in the juice therefore considerably degrades the anthocyanins of Hibiscus sabdariffa L. from the first month of storage at 4°C.