Modeling the formation and composition of secondary organic aerosol from diesel exhaust using parameterized and semi-explicit chemistry and thermodynamic models

2017 Spring.Includes bibliographical references.Laboratory-based studies have shown that diesel-powered sources emit volatile organic compounds that can be photo-oxidized in the atmosphere to form secondary organic aerosol (SOA); in some cases, this SOA can exceed direct emissions of particulate matter (PM); PM is a criteria pollutant that is known to have adverse effects on air quality, climate, and human health. However, there are open questions surrounding how these laboratory experiments can be extrapolated to the real atmosphere and how they will help identify the most important species in diesel exhaust that contribute to SOA formation. Jathar et al. (2017) recently performed experiments using an oxidation flow reactor (OFR) to measure the photochemical production of SOA from a diesel engine operated at two different engine loads (idle, load), two fuel types (diesel, biodiesel) and two aftertreatment configurations (with and without an oxidation catalyst and particle filter). In this work, we will use two different SOA models, namely the volatility basis set (VBS) model and the statistical oxidation model (SOM), to simulate the formation, evolution and composition of SOA from the experiments of Jathar et al. (2017). Leveraging recent laboratory-based parameterizations, both frameworks accounted for a semi-volatile and reactive POA, SOA production from semi-volatile, intermediate-volatility and volatile organic compounds (SVOC, IVOC and VOC), NOx-dependent multigenerational gas-phase chemistry, and kinetic gas/particle partitioning. Both frameworks demonstrated that for model predictions of SOA mass and elemental composition to agree with measurements across all engine load-fuel-aftertreatment combinations, it was necessary to (a) model the kinetically-limited gas/particle partitioning likely in OFRs and (b) account for SOA formation from IVOCs (IVOCs were found to account for more than four-fifths of the model-predicted SOA). Model predictions of the gas-phase organic compounds (resolved in carbon and oxygen space) from the SOM compared favorably to gas-phase measurements made using a Chemical Ionization Mass Spectrometer (CIMS) that, qualitatively, substantiated the semi-explicit chemistry captured by the SOM and the measurements made by the CIMS. Sensitivity simulations suggested that (a) IVOCs from diesel exhaust could be modeled using a single surrogate species with an SOA mass yield equivalent to a C15 or C17 linear alkane for use in large-scale models, (b) different diesel exhaust emissions profiles in the literature resulted in the same SOA production as long as IVOCs were included and (c) accounting for vapor wall loss parameterizations for the SOA precursors improved model performance. As OFRs are increasingly used to study SOA formation and evolution in laboratory and field environments, there is a need to develop models that can be used to interpret the OFR data. This work is one example of the model development and application relevant to the use of OFRs

A Framework for Improved Intrusion Detection and Countermeasure Selection in Cloud Systems

No Abstrac

Analysis of dual-gripper manipulators and finite element analysis of the flexible laminated hose for underground storage tank cleanup

The second generation long-reach manipulator - the dual-gripper Phase 3 Remote Tool Delivery (RTD) system has been developed to retrieve radioactive waste from underground storage tanks with internal structural members. The RTD is equipped with two grippers, one at each end of the system, to grasp the structural member. A vertical translation mechanism is also added to the system that enables the vertical motion inside the tank. This special feature provides greater dexterity and flexibility. Two operating open-chain configurations are considered and modeled. The first configuration is that gripper 1 grasps the structural member and gripper 2 is free to perform a designated task. The other configuration is that gripper 2 grasps the structural member and gripper 1 is free to move. The kinematics, dynamics and simulation of the system are emphasized. Finite Element Analysis (FEA) of the flexible laminated hose used to convey radioactive waste materials was investigated to learn about its structural behavior. The hose is considered relatively fixed at one end (the outlet) and subjected to different loading conditions at the inlet. Liquid (mixture of water and sludge) with high viscosity is sucked through the hose using a vacuum pressure. The software package employed for FEA is ANSYS 5.2. A total of 200 cases, with different X, Y and Z loading conditions at the inlet, for the hose under the consideration with or without vacuum pressure have been analyzed. Numerical results and the ANSYS graphic outputs provided for each case include the deformation, stress distribution and strain distribution throughout the hose

Social facilitation of polydipsia as an animal model of compulsive behavior

Behavior excesses are a key feature in many psychiatric diagnoses. Obsessive-compulsive disorder (OCD), in particular, is almost entirely defined in terms of behavior excesses. Although much research has been conducted on OCD treatment, very little research has focused on understanding how these compulsive behaviors are acquired. The few theories advanced to explain the etiology of OCD compulsions have significant limitations. The purpose of this study is to test social facilitation as a potential mechanism through which compulsive behaviors are acquired, via an animal model. Schedule-induced polydipsia (SIP) was employed as the behavior of interest because there is empirical support indicating it as an animal model of compulsive behavior. The fundamental issue was to determine if naïve rats exposed to rats that drank reliably would (1) show elevated rates of drinking as a result of the exposure, and then (2) acquire SIP more rapidly than rats without that exposure. Twenty-four male Sprague-Dawley rats were randomly designated to be (1) drinking model rats, (2) drinking naïve rats, (3) feeding control model rats, (4)feeding control naïve rats, (5) social contact control model rats, (6) social contact control naïve rats, and (7) naïve control rats. SIP was established in the drinking model rats using a fixed-time 60-second schedule of food delivery (FT-60) with water available. Once stable drinking occurred, the models and their matched naïve rat were placed in the same experimental chamber to determine if drinking in the naïve rat would be socially facilitated. Strong individual differences in drinking by the naïve rats were observed. However, the overall indications were that social facilitation may play a role in enhancing the acquisition of SIP and that social facilitation may be a factor in the development of compulsive behavior

Modified Micro-Deval Procedure for Polishing of Fine Asphalt Mix Aggregates

A procedure combining Micro-Deval and 2nd generation Aggregate Imaging Measurement System (AIMS-II) test procedures was developed to characterize aggregate polishing characteristics, and in turn, provide a means for qualifying aggregate sources for friction purposes. This study focused on the minimum number of aggregate particles, aggregate sizes, and the number of revolutions in the Micro-Deval test. Only two aggregate sources were included in this study. Thus, further analyses are needed for wider range of aggregate sources/mineralogical properties in order to establish the minimum required aggregate shape properties for friction.IDOT-R27-SP36Ope

Ofloxacin induced hypersensitivity reaction

Ofloxacin is a commonly used antimicrobial agent to combat various infections. The adverse profile of quinolones includes gastrointestinal symptoms, which are the most frequent, neuropsychiatric symptoms, hematologic abnormalities are less common. We report a rare case of ofloxacin induced hypersensitivity reaction in a 57 year old female patient with complaints of rashes over the axilla, upper limb and back, abdomen, thorax associated with exfoliation of skin all over the axilla associated with severe itching. Based on history and clinical examination patient was diagnosed as ofloxacin induced hypersensitivity reaction and was successfully treated with antihistamines and corticosteroids. Pharmacovigilance should be a part of patient care in order to reduce occurrence of adverse drug reaction and also encourage practitioners in reporting so as to gather more and more data regarding adverse drug reactions

Phenobarbital induced Stevens-Johnson syndrome: a case report

Stevens-Johnson Syndrome (SJS) is a life-threatening acute hypersensitive reaction affecting the skin and mucous membranes. We report a case with SJS likely induced by phenobarbitone during the switch of sodium valproate and phenobarbitone regimen. The patient reported fever with fluid-filled lesions all over the body and redness and burning sensation of both the eyes. Peeling of the skin due to rupture of the fluid-filled lesions and pigmentation on the skin for 10 days. Based on a physical examination and laboratory findings, he was diagnosed with Phenobarbital induced Stevens-Johnson syndrome. The patient was administered systemic steroid therapy and treated symptomatically and finally replaced with phenobarbitone and sodium valproate. During the hospital stay, the patient appeared normal and the skin lesions disappeared, after two weeks of treatment

Maintenance scheduling and inventory control policy in aviation industry : An integrated framework.

Airlines seek to minimise operating costs, in all aspect of business areas. Some of these areas are the aircraft maintenance and inventory control policies associated.Maintenance is one of the essential operations in aviation industry. Any shortcoming in maintenance causes reducing in the income rate.In addition, there is a direct relationship between maintenance and inventory department in any company is a vital to guarantee the availability of spare parts to carry out the required maintenance.Therefore, this research presents an integrated framework for maintenance scheduling and inventory control policies in aviation industry, aiming to minimise the maintenance cost by addressing a models for determining the optimum maintenance scheduling for aircraft components and its inventory control policy. The interval between maintenance for the components is optimised by minimising the total cost. This consists of labour cost, spare parts cost and delay cost etc.A decision to replace a component must also be taken when a component cannot attain the minimum reliability.Mathematical models are developed to calculate the expected costs based on the cost of corrective, preventive maintenance and the probability of failure. The maintenance scheduling mathematical model is developed to act as a maintenance decision making model to determine the optimum preventive maintenance interval of the expensive aircraft components. A decision making inventory control model to balance the cost of repair and purchase cost is developed and will be integrated with the scheduling maintenance to guarantee the availability of the required components and act as an integrated framework, this would facilitate the decision making process in aviation industry in relation to scheduling and inventory policies