A flotation control system to optimise performance using peak air recovery

Automatic control of industrial flotation cells and circuits presents a set of significant challenges due to the number of variables, the sensitivity of flotation cells to variation in these variables and the complexity of predicting flotation performance and/or developing a strategy for optimisation. Air recovery, a measure of froth stability, has been shown to pass through a peak as flotation cell aeration increases. Furthermore, the air rate at which the peak air recovery (PAR) is obtained results in optimal flotation performance, whether improved concentrate grade, recovery or both grade and recovery. Peak air recovery, therefore, presents a clear optimising control strategy for the operation of flotation cells which is generic to all flotation cells regardless of position in the flotation circuit. In this study, a novel control system based on PAR is developed and demonstrated using a large continuous laboratory flotation cell. In this study, a direct search optimisation algorithm based on the GSS (generating set search) methodology was developed using a 70 l continuous flotation cell operating with a two-phase system (surfactant solution and air only). Characterisation of the laboratory system showed that it was stable for up to 6 h and exhibited a reproducible peak in air recovery. A dynamic model of the response of the system with regards to changes in air recovery was developed that allowed simulations of the proposed optimising control system to be carried out. The optimisation algorithm was then applied to the experimental system. The trialled GSS algorithm was shown to find the PAR air rate when starting above, below and at the PAR air rate, and additionally with a disturbance introduced into the system. While the direct search approach can be slow, it is simple and robust. This demonstrates an innovative approach to optimising control for froth flotation and is the first application of froth stability maximisation for flotation control

Hot spots of glacier mass balance variability in Central Asia

The Tien Shan and Pamir mountains host over 28,000 glaciers providing essential water resources for increasing water demand in Central Asia. A disequilibrium between glaciers and climate affects meltwater release to Central Asian rivers, challenging the region's water availability. Previous research has neglected temporal variability. We present glacier mass balance estimates based on transient snowline and geodetic surveys with unprecedented spatiotemporal resolution from 1999/00 to 2017/18. Our results reveal spatiotemporal heterogeneity characterized by two mass balance clusters: (a) positive, low variability, and (b) negative, high variability. This translates into variable glacial meltwater release (≈1–16%) of annual river runoff for two watersheds. Our study reveals more complex climate forcing-runoff responses and importance of glacial meltwater variability for the region than suggested previously.ISSN:0094-8276ISSN:1944-800

Impact of HIV on admissions and deaths in a tuberculosis hospital - recommendations for admission and discharge criteria

Mortality and HIV prevalence rose concordantly at Brooklyn Chest Hospital from 1998 to 2001. Death and unconfirmed tuberculosis (TB) (15% of adult admissions in a sample from 2000) were associated with HIV seropositivity. Excluding unconfirmed TB and shortening length of stay would increase the number of patients able to benefit from hospitalisation

Fabrication of mesoporous carbons coated monolith via evaporative induced self-assembly approach: effect of solvent and acid concentration on pore architecture

Carbon coating onto monolith through soft-template approach have been accomplished by means of evaporative induced self-assembly (EISA). Variation in acid and alcohol content on monolith's surface properties was studied, while β-carotene was used as a modelled adsorbate. The pore architecture of adsorbent samples was analysed through corresponding surface chemistry, N2 sorption isotherm, pore size distribution (PSD) plot, Brunauer–Emmett–Teller (BET), Barett–Joyner–Halenda (BJH) model and scanning electron microscopy (SEM). SEM images displayed a well-covered interconnected worm-like framework of carbonaceous materials over monolith surface. Surface chemistry studies revealed dominance of acid functionalities over adsorbent samples surface, while basic functionalities remain unaltered. Carbon loading increased with increase in acid concentration, while it decreased with increase in alcohol content. The adsorbent surface area decreased with increase in acid concentration and alcohol content. The β-carotene adsorption capacities on synthesized samples varied between 179.60 (optimum) and 112.56 mg/g (lower), respectively. Optimum β-carotene adsorption was observed on samples MC0.2 and MC5 with alcohol and acid content of 5 mL and 0.2 mL, respectively

Melting and crystallisation behaviour of soybean oil in blend with palm oil-based diacylglycerol

In the present work, the physicochemical properties namely fatty acid composition (FAC), iodine value (IV), acylglycerol content and thermal profiles of palm-based diacylglycerol (PDAG) in blend with soybean oil (SBO) at different concentrations (0-100 wt %) were evaluated. The Fourier-transform infrared spectroscopy (FTIR) spectra were determined at mid-infrared region to assign the functional groups. SBO exhibited the same absorption bands as PDAG except at wavelength of 1711, 1450, 1359, 850 and 779 cm-1. This phenomenon indicated that the absorption frequency of the binary mixtures greatly depended on the composition of oil samples. IV of the oil blends was found to decrease from 131.09 ± 0.88 I2/100 g to 51.55 ± 0.60 I2/100 g with increasing PDAG concentrations due to the reduced degree of unsaturation. Generally, binary blends with an increasing PDAG concentration showed a decrease in linoleic acid (C18:2) as well as increase in oleic acid (C18:1) and palmitic acid (C16:0) contents. The DAG content for all the blends increased from 5.15 ± 1.40% to 87.80 ± 0.33% and TAG content decreased from 94.85 ± 1.40% to 12.20 ± 0.33% in tandem with increasing PDAG content. Incorporation of PDAG into SBO significantly affected the crystallisation and melting profiles of SBO

Rapid fluvial remobilization of sediments deposited by the 2021 Chamoli disaster, Indian Himalaya

High-magnitude mass flows can have a pervasive geomorphological legacy, yet the short-term response of valley floors to such intense disturbances is poorly known and poses significant observational challenges in unstable landscapes. We combined satellite remote sensing, numerical modeling, and field observations to reconstruct the short-term geomorphological response of river channels directly affected by the 7 February 2021 ice-rock avalanche−debris flow in Chamoli district, Uttarakhand, India. The flow deposited 10.4 ± 1.6 Mm3 of sediment within the first 30 km and in places reset the channel floor to a zero-state condition, requiring complete fluvial re-establishment. In the 12 months post-event, 7.0 ± 1.5 Mm3 (67.2%) of the deposit volume was removed along a 30-km-long domain and the median erosion rate was 2.3 ± 1.1 m a−1. Most sediment was removed by pre-monsoon and monsoon river flows, which conveyed bedload waves traveling at 0.1−0.3 km day−1 and sustained order-of-magnitude increases in suspended sediment concentrations as far as 85 km from the event source. Our findings characterize a high-mountain fluvial cascade with a short relaxation time and high resilience to a high-magnitude geomorphological perturbation. This system response has wider implications, notably for water quality and downstream hydropower projects, which may be disrupted by elevated bedload and suspended sediment transport

Gene Regulation in the Pi Calculus: Simulating Cooperativity at the Lambda Switch

Part of the Lecture Notes in Computer Science book series (LNCS, volume 4230).Also part of the Lecture Notes in Bioinformatics book sub series (volume 4230).International audienceWe propose to model the dynamics of gene regulatory networks as concurrent processes in the stochastic pi calculus. As a first case study, we show how to express the control of transcription initiation at the lambda switch, a prototypical example where cooperative enhancement is crucial. This requires concurrent programming techniques that are new to systems biology, and necessitates stochastic parameters that we derive from the literature. We test all components of our model by exhaustive stochastic simulations. A comparison with previous results reported in the literature, experimental and simulation based, confirms the appropriateness of our modeling approach

Characteristics and Treatment Outcomes of Patients with MDR and XDR Tuberculosis in a TB Referral Hospital in Beijing: A 13-Year Experience

Background: Information on treatment outcomes among hospitalized patients with multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are scarce in China. Methodology/Principal Findings: We conducted this retrospective study to analyze the characteristics and treatment outcomes in MDR- and XDR-TB patients in the 309 Hospital in Beijing, China during 1996-2009. Socio-demographic and clinical data were retrieved from medical records and analyzed. Logistic regression analysis was performed to identify risk factors associated with poor treatment outcomes and Cox proportional hazards regression model was further used to determine risk factors associated with death in TB patients. Among the 3,551 non-repetitive hospitalized TB patients who had drug susceptibility testing (DST) results, 716 (20.2%) had MDR-TB and 51 (1.4%) had XDR-TB. A total of 3,270 patients who had medical records available were used for further analyses. Treatment success rates (cured and treatment completed) were 90.9%, 53.4% and 29.2% for patients with non-MDR-TB, patients with MDR-TB excluding XDR-TB and patients with XDR-TB, respectively. Independent risk factors associated with poor treatment outcomes in MDR-TB patients included being a migrant (adjusted OR = 1.77), smear-positivity at treatment onset (adjusted OR = 1.94) and not receiving 3 or more potentially effective drugs (adjusted OR = 3.87). Independent risk factors associated with poor treatment outcomes in XDR-TB patients were smear-positivity at treatment onset (adjusted OR = 10.42) and not receiving 3 or more potentially effective drugs (adjusted OR = 14.90). The independent risk factors associated with death in TB patients were having chronic obstructive pulmonary disease (adjusted HR = 5.25) and having hypertension (adjusted HR = 4.31). Conclusions/Significance: While overall satisfactory treatment success for non-MDR-TB patients was achieved, more intensive efforts should be made to better manage MDR- and XDR-TB cases in order to improve their treatment outcomes and to minimize further emergence of so-called totally drug-resistant TB cases. © 2011 Liu et al.published_or_final_versio