62 research outputs found
Coagulation for treatment of swine slaughterhouse wastewater
In this study, wastewater taken from the Nam Phong swine slaughterhouse, Ho Chi Minh City, was used to evaluate the treatment efficiency of common coagulants, including Alum (Aluminum Sulfate - Al2(SO4)3.18H2O), Poly-Aluminum Chloride (PAC), and Ferrous Sulfate (FeSO4.7H2O), using a jar-test system. The experiments were conducted using the one-factor-at-a-time method to examine three variables which are pH, stirring speed, and coagulant dosage. The results showed that both Alum and PAC perform over 90% removal of colour, turbidity, COD, and total phosphorus (TP) from slaughterhouse wastewater at pH 7 with a stirring speed of 75 revolutions per minute (RPM) and average coagulant dosages of 450 mg/L for Alum and 550 mg/L for PAC. Meanwhile, under the appropriate conditions of pH equal to 10 and 75 RPM with a chemical dosage of 350 mg/L, COD and TP removal efficiencies by Ferrous Sulfate exceed 87%, but those of turbidity and colour only reach 25%. This finding could be a promising coagulation method as a pre-treatment for the swine slaughterhouse wastewater
Modelling and Fast Terminal Sliding Mode Control for Mirror-based Pointing Systems
In this paper, we present a new discrete-time Fast Terminal Sliding Mode
(FTSM) controller for mirror-based pointing systems. We first derive the
decoupled model of those systems and then estimate the parameters using a
nonlinear least-square identification method. Based on the derived model, we
design a FTSM sliding manifold in the continuous domain. We then exploit the
Euler discretization on the designed FTSM sliding surfaces to synthesize a
discrete-time controller. Furthermore, we improve the transient dynamics of the
sliding surface by adding a linear term. Finally, we prove the stability of the
proposed controller based on the Sarpturk reaching condition. Extensive
simulations, followed by comparisons with the Terminal Sliding Mode (TSM) and
Model Predictive Control (MPC) have been carried out to evaluate the
effectiveness of the proposed approach. A comparative study with data obtained
from a real-time experiment was also conducted. The results indicate the
advantage of the proposed method over the other techniques.Comment: In Proceedings of the 15th International Conference on Control,
Automation, Robotics and Vision (ICARCV 2018
Automatic Crack Detection in Built Infrastructure Using Unmanned Aerial Vehicles
This paper addresses the problem of crack detection which is essential for
health monitoring of built infrastructure. Our approach includes two stages,
data collection using unmanned aerial vehicles (UAVs) and crack detection using
histogram analysis. For the data collection, a 3D model of the structure is
first created by using laser scanners. Based on the model, geometric properties
are extracted to generate way points necessary for navigating the UAV to take
images of the structure. Then, our next step is to stick together those
obtained images from the overlapped field of view. The resulting image is then
clustered by histogram analysis and peak detection. Potential cracks are
finally identified by using locally adaptive thresholds. The whole process is
automatically carried out so that the inspection time is significantly improved
while safety hazards can be minimised. A prototypical system has been developed
for evaluation and experimental results are included.Comment: In proceeding of The 34th International Symposium on Automation and
Robotics in Construction (ISARC), pp. 823-829, Taipei, Taiwan, 201
Removal of inorganic nutrient and organic carbon from wastewater of Binh Dien market using the green alga Chlorella sp.
Traditional markets play a major role in socio-economics and constitutes a significant aspect of Vietnamese culture. However, wastewater streams discharged from the markets are generally characterized by a lot of inorganic nutrients and organic substances originated from fresh food processing units. They could lead to serious water contamination if discharged without proper treatment. This study applied microalgae Chlorella sp. for eliminating inorganic nutrients (NO3--N, NH4+-N and PO43--P) and organic carbon (Chemical oxygen demand-COD) from wastewater of the Binh Dien market. The removal efficiencies reached for NH4+-N > 86%, for NO3--N > 72%, and for PO43--P > 69%, respectively, at algal density of 49 x 104 cell mL-1, and for COD > 96% at algal density of 35 x 104 cell mL-1 after five cultivating days. The effluence satisfied the Vietnamese standard, column B, of the National technical regulation on industrial wastewater (QCVN 40:2011/BTNMT). The results demonstrated that the culture system composed of green algal Chlorella sp. could be a potential candidate for the removal of nutrients and organic carbon by a wastewater treatment process from the Binh Dien market
Modelling European Business Cycles (EBC Model): A Macroeconometric Model of Germany ; Version March 2005
Room-temperature ferromagnetism in monolayer WSe2 semiconductor via vanadium dopant
Diluted magnetic semiconductors including Mn-doped GaAs are attractive for
gate-controlled spintronics but Curie transition at room temperature with
long-range ferromagnetic order is still debatable to date. Here, we report the
room-temperature ferromagnetic domains with long-range order in semiconducting
V-doped WSe2 monolayer synthesized by chemical vapor deposition. Ferromagnetic
order is manifested using magnetic force microscopy up to 360K, while retaining
high on/off current ratio of ~105 at 0.1% V-doping concentration. The
V-substitution to W sites keep a V-V separation distance of 5 nm without V-V
aggregation, scrutinized by high-resolution scanning transmission-electron
microscopy, which implies the possibility of the Ruderman-Kittel-Kasuya-Yoshida
interaction (or Zener model) by establishing the long-range ferromagnetic order
in V-doped WSe2 monolayer through free hole carriers. More importantly, the
ferromagnetic order is clearly modulated by applying a back gate. Our findings
open new opportunities for using two-dimensional transition metal
dichalcogenides for future spintronics.Comment: 16 pages, 4 figure
Crystal structure of 4-amino-3-(thio-phen-3-ylmeth-yl)-1<i>H</i>-1,2,4-triazole-5(4<i>H</i>)-thione.
In the title compound, C7H8N4S2, the thio-phene ring shows rotational disorder over two orientations in a 0.6957 (15):0.3043 (15) ratio. The plane of the 1,2,4-triazole ring makes a dihedral angle of 75.02 (17)° with the major-disorder component of the thiophene ring. In the crystal, two types of inversion dimers, described by the graph-set motifs R22(8) and R22(10), are formed by N-H⋯S inter-actions. Chains of mol-ecules running in the [101] direction are linked by weaker N-H⋯N inter-actions. The thio-phene ring is involved in π-π and C-H⋯π inter-actions
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The impact of environmental and climatic variation on the spatiotemporal trends of hospitalized pediatric diarrhea in Ho Chi Minh City, Vietnam.
It is predicted that the integration of climate-based early warning systems into existing action plans will facilitate the timely provision of interventions to diarrheal disease epidemics in resource-poor settings. Diarrhea remains a considerable public health problem in Ho Chi Minh City (HCMC), Vietnam and we aimed to quantify variation in the impact of environmental conditions on diarrheal disease risk across the city. Using all inpatient diarrheal admissions data from three large hospitals within HCMC, we developed a mixed effects regression model to differentiate district-level variation in risk due to environmental conditions from the overarching seasonality of diarrheal disease hospitalization in HCMC. We identified considerable spatial heterogeneity in the risk of all-cause diarrhea across districts of HCMC with low elevation and differential responses to flooding, air temperature, and humidity driving further spatial heterogeneity in diarrheal disease risk. The incorporation of these results into predictive forecasting algorithms will provide a powerful resource to aid diarrheal disease prevention and control practices in HCMC and other similar settings
A prospective multi-center observational study of children hospitalized with diarrhea in Ho Chi Minh City, Vietnam.
We performed a prospective multicenter study to address the lack of data on the etiology, clinical and demographic features of hospitalized pediatric diarrhea in Ho Chi Minh City (HCMC), Vietnam. Over 2,000 (1,419 symptomatic and 609 non-diarrheal control) children were enrolled in three hospitals over a 1-year period in 2009-2010. Aiming to detect a panel of pathogens, we identified a known diarrheal pathogen in stool samples from 1,067/1,419 (75.2%) children with diarrhea and from 81/609 (13.3%) children without diarrhea. Rotavirus predominated in the symptomatic children (664/1,419; 46.8%), followed by norovirus (293/1,419; 20.6%). The bacterial pathogens Salmonella, Campylobacter, and Shigella were cumulatively isolated from 204/1,419 (14.4%) diarrheal children and exhibited extensive antimicrobial resistance, most notably to fluoroquinolones and third-generation cephalosporins. We suggest renewed efforts in generation and implementation of policies to control the sale and prescription of antimicrobials to curb bacterial resistance and advise consideration of a subsidized rotavirus vaccination policy to limit the morbidity due to diarrheal disease in Vietnam
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