Real time optimization of chemical processes

Due to current changes in the global market with increasing competition, strict bounds on product specifications, pricing pressures, and environmental issues, the chemical process industry has a high demand for methods and tools that enhance profitability by reducing the operating costs using limited resources. Real time optimization (RTO) strategies combine process control and economics, and have gone through much advancement during the last few decades. A typical real time optimization application is model based and requires the solution of at least three (usually) nonlinear programming problems, such as combined gross error detection and data reconciliation, parameter estimation and economic optimization. A successful implementation of RTO requires fast and accurate solution of these stated nonlinear programming problems.Current real time optimization strategies wait for steady state after a disturbance enters the process. If, during this wait, another disturbance enters into the system, it will increase the transition time significantly. An alternative, real time evolution (RTE), calculates the new set-points using only disturbance information and the new set-points are implemented in small step changes to a supervisory control system such as model predictive control (MPC) or can be implemented directly to the regulatory control layer. RTE ignores the important part of data screening therefore there is no surety that the calculated set-points represents current plant conditions. The main contribution of this thesis is to investigate the possibility of implementing new set-points without waiting for steady state. Two case studies, the Williams-Otto reactor and an integrated plant (the Williams-Otto reactor extended to include flash drum and large recycle stream), were used for analysis. The application of RTE, RTO and MPC were discussed and compared for the case studies to evaluate the performance in terms of the theoretical profit achieved.A new strategy, dynamic-RTO (D-RTO), based on modified dynamic data reconciliation (DDR) strategy and translated steady state model, was also developed for systems with significant bias and process noise. In the D-RTO strategy, the residual terms of the steady state model were calculated from the reconciled values. These residual terms were translated subsequently into the steady state model. Due to the translation there is no need for calculating set-point changes in small steps. The formulation of the DDR strategy is based on control vector parameterization techniques. D-RTO was compared with RTE and RTO for the two case studies. The results obtained show that RTE can lead to an unstable control if used without taking into account process and controller dynamics. For measurements having bias, the DDR strategy can be used with the assumption that the variables with bias are unmeasured and are calculated implicitly. The D-RTO strategy is able to deal with constant and changing bias, and is able to decrease profit losses during transitions. D-RTO is a good alternative to steady state RTO, for processes with frequent disturbances, where RTO implementation due to its steady state nature may not be justifiable

Cerebral deep venous thrombosis: case report and literature review

The case of a 28 years old woman presenting with headache, drowsiness and vomiting of a short duration, is presented. She was diagnosed as deep cerebral venous thrombosis on the basis of MRI findings. Treatment with heparin gave completed recovery

Planar SIW leaky wave antenna with electronically reconfigurable E-and H-plane scanning

This paper reports on a novel technique of switching radiation characteristics electronically between E-and H-planes of planar Substrate Integrated Waveguide Leaky Wave Antennas (SIW-LWAs). The leaky wave mode is achieved through increasing the pitch of bounding metallic via posts on one side of SIW transmission section. The radiation switching is achieved by extending the top and bottom metallic planes to a distance of 1 mm along the leakage side. The extended section acts as a parallel plate section which is conveniently connected or disconnected from the leaking side of SIW through PIN diodes. The ‘ON’ state of PIN diodes extends the metal guides and results in the H-plane leakage whereas ‘OFF’ state of PIN diodes truncates the extended metal earlier and alter the leakage line boundary condition towards E-plane. The whole concept is validated by series of simulations followed by the realization and testing of the SIW-LWA. The measured radiation pattern scans about 54° in the E-plane between 10.0 GHz to 11.7 GHz, and 58° in the H-plane from 9 GHz to 10.6 GHz. The proposed topology is a suitable candidate for remote sensing and airborne applications

Methyl 4-hy­droxy-2-meth­oxy­carbonyl­methyl-1,1-dioxo-1,2-dihydro-1λ6,2-benzothia­zine-3-carboxyl­ate1

There are two independent mol­ecules in the asymmetric unit of the title compound, C13H13NO7S, which have almost identical geometries. The thia­zine ring adopts a sofa conformation in both mol­ecules and the mol­ecular conformations are stabilized by intramolecular O—H⋯O hydrogen bonds. Inter­molecular C—H⋯O hydrogen bonds stabilize the crystal packing

2-Chloro-4-(2-iodo­benzene­sulfonamido)­benzoic acid

In the title compound, C13H9ClINO4S, the dihedral angle between the aromatic rings is 81.04 (17)°. The disposition of the I and Cl atoms attached to the two rings is anti. In the crystal, mol­ecules are connected via O—H⋯O and N—H⋯O hydrogen bonds

Epidemiology of Extended Spectrum Beta Lactamase Producing Gram Negative Rods

OBJECTIVE: To estimate the distribution of ESBL producing capacity among different Gram negative isolates along with specimen and department wise prevalence in a tertiary care hospital. METHODOLGY: This cross-sectional study was conducted at the Microbiology section of Pathology Department, Allama Iqbal Medical College, Lahore, Pakistan, from August 2016 to January 2017. Total of 437 clinical samples were collected from different wards of Jinnah Hospital, Lahore. Sample was cultured on Blood agar, MacConkey’s agar, chocolate agar, CLED agar. After the identification every Gram negative isolate was further processed for the antibiotic susceptibility testing following Modified Kirby Bauer disc diffusion method. ESBL detection was performed by the combination drugs disc method using ceftriaxone + clavulanic acid (30/10 µg) in case of Enterobacteriacae, ceftazidime + clavulanic acid (30/10µg) in case of Pseudomonas species. RESULTS: Among total 437 patients male and female were 61% and 39% respectively, overall 21.5% (94/437) were ESBl producers. Distribution of ESBL producers was as followed Acinetobacter spp 22.3% (31/139), Escherichia coli 37.5% (27/72), Klebsiella spp 31.9% (15/47), Pseudomonas aeruginosa 8.4% (13/154) and Proteus spp 32.0% (8/25). Department wise ESBL positivity was as followed Surgical units 25.6% (32/125) Medical unit 31.9% (30/94), Burn centre 10% (8/80), ICU 20% (8/40) Surgical Allied 11.7% (4/34), Medical Allied 6.2% (2/32), Neurology 36.3% (8/22), Gynaecology 28.5% (2/7) and Dermatology 33.3% (1/3). CONCLUSION: High percentage of ESBL positivity seen in Escherichia coli and Proteus spp, among departments neurology and medical unit is holding maximum positivity. High frequency of ESBL producing Gram negative isolates strongly recommend its detection and management accordingly. It can lead to treatment failures in Gram negative rods associated infections

Heavy metals in selected vegetables from markets of Faisalabad, Pakistan

Two hundred ten samples of selected vegetables (okra, pumpkin, tomato, potato, eggplant, spinach, and cabbage) from Faisalabad, Pakistan, were analyzed for the analysis of heavy metals: cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg). Inductively coupled plasma optical emission spectrometry was used for the analysis of heavy metals. The mean levels of Cd, Pb, As, and Hg were 0.24, 2.23, 0.58, and 7.98 mg/kg, respectively. The samples with Cd (27%), Pb (50%), and Hg (63%) exceeded the maximum residual levels set by the European Commission. The mean levels of heavy metals found in the current study are high and may pose significant health concerns for consumers. Furthermore, considerable attention should be paid to implement comprehensive monitoring and regulations

N-(2-Bromo­phen­yl)-4-methyl-N-(4-methyl­phen­ylsulfon­yl)benzene­sulfonamide

In the title compound, C20H18BrNO4S2, the mean planes formed by the toluene substituents are inclined at a dihedral angle of 45.34 (8)°. The bromo­benzene group is disordered over two positions with an occupancy ratio of 0.74:0.26, resulting in two conformations of the ring; the two rings are oriented at a dihedral angle of 6.6 (6)° with each other. In the crystal structure, weak C—H⋯O inter­actions connect the mol­ecules in a zigzag manner along the a axis