A new leak location method based on leakage acoustic waves for oil and gas pipelines

In order to study a new leak detection and location method for oil and natural gas pipelines based on acoustic waves, the propagation model is established and modified. Firstly, the propagation law in theory is obtained by analyzing the damping impact factors which cause the attenuation. Then, the dominant-energy frequency bands of leakage acoustic waves are obtained through experiments by wavelet transform analysis. Thirdly, the actual propagation model is modified by the correction factor based on the dominant-energy frequency bands. Then a new leak detection and location method is proposed based on the propagation law which is validated by the experiments for oil pipelines. Finally, the conclusions and the method are applied to the gas pipelines in experiments. The results indicate: the modified propagation model can be established by the experimental method; the new leak location method is effective and can be applied to both oil and gas pipelines and it has advantages over the traditional location method based on the velocity and the time difference. Conclusions can be drawn that the new leak detection and location method can effectively and accurately detect and locate the leakages in oil and natural gas pipelines.     

Effectiveness of the CDC HEADS UP online training on healthcare providers’ mTBI knowledge and self-efficacy

Background: Many healthcare providers do not consistently implement recommendations contained in clinical guidelines on mild traumatic brain injury (mTBI). As such, the Centers for Disease Control and Prevention (CDC) created the HEADS UP to Healthcare Providers online training to promote uptake of five key recommendations in the CDC Pediatric mTBI Guideline. Methods: Using data from modules in the CDC HEADS UP to Healthcare Providers online training, healthcare providers’ self-reported knowledge and self-efficacy prior to and immediately following completion of the training was analyzed. Results: Improvements for 8 out of the 10 knowledge questions had a high level of practical significance. The knowledge question with the highest level of practical significance pre- to post-test improvement was for the key guideline recommendation on neuroimaging (pre-test correct: 70.2%; post-test correct: 87.8%; (p < 0.0001, Cohen’s g = 0.39). Four out of the six questions had a self-efficacy level increase of a high level of practical significance (r > 0.50) between the pre- and post-tests. The self-efficacy question with pre- to post-test improvement with the highest level of practical significance was “I am confident in my ability to manage the return to sports progression for my patients” (p < 0.001; r = 0.54). Conclusions: The HEADS UP to Healthcare Providers online training led to significant improvements in knowledge and self-efficacy related to mTBI diagnosis and management. Expanded use of this training among healthcare providers who commonly provide care for pediatric patients with mTBI may be beneficial. Practical Applications: This study highlights several factors guideline developers may take into consideration when creating an implementation tool, such as using health behavior theories, working with partners and key stakeholders, and focusing on digital-based tools.     

To reduce or to cease: A systematic review and meta-analysis of quantitative studies on self-regulation of driving

Introduction: The ability to remain safe behind the wheels can become arduous with aging, yet important for sustaining local travel needs. This review aimed to explore safe mobility issues involving older adults and gain a broad understanding of older drivers' self-regulatory driving practices and motivators behind such behavioral changes, including strategies adopted to reduce or cease driving while maintaining safe mobility. Methods: A systematic literature search was performed on 11 online databases for quantitative studies describing self-regulation of driving amongst older adults aged 60 years and above from database inception until December 2018. Data were described narratively and, where possible, data were pooled using random-effects meta-analysis. Results: Of the 1556 studies identified, 54 studies met the inclusion criteria and 46 studies were included in the meta-analyses. All included studies examined car drivers only. Older adults who were single or female were found to be at higher odds of driving cessation. Physical fitness, mental health, social influence, and support systems received by older adults were important driving forces influencing mobility and adjustments made in their travel patterns. Conclusions: Driving self-regulation amongst older adults is a multifaceted decision, impacting mobility and mental health. Therefore, future interventions and support systems should not only create opportunities for retaining mobility for those who have ceased driving, but also promote better psychological and social well-being for regulators and for those who are transitioning from driving to non-driving status. Practical applications: (a) Engage and educate older adults about self-regulation, including strategies that can be adopted and non-car mobility options available. (b) Expand the research focus to explore potential interactions of factors facilitating or hindering the transition process to develop a more comprehensive framework of self-regulation. (c) Encourage ongoing research to formulate, monitor, and evaluate the effectiveness of policies and interventions implemented. (d) Expand the research horizon to explore and understand the perspectives of older adults from developing countries.     

Chlorinated naphthalene formation from the oxidation of dichlorophenols

Polychlorinated naphthalenes (PCNs) formed along with dibenzo-p-dioxin and dibenzofuran products in the slow combustion of dichlorophenols (DCPs) at 600 degrees C were identified. Each DCP reactant produced a unique set of PCN products. Major PCN congeners observed in the experiments were consistent with products predicted from a mechanism involving an intermediate formed by ortho-ortho carbon coupling of phenoxy radicals; polychlorinated dibenzofurans (PCDFs) are formed from the same intermediate. Tautomerization of the intermediate and H2O elimination produces PCDFs; alternatively, CO elimination to form dihydrofulvalene and fusion produces naphthalenes. Only trace amounts of tetrachloronaphthalene congeners were formed, suggesting that the preferred PCN formation pathways from chlorinated phenols involve loss of chlorine. 3,4-DCP produced the largest yields of PCDF and PCN products with two or more chlorine substituents. 2,6-DCP did not produce tri- or tetra-chlorinated PCDF or PCN congeners. It did produce 1,8-DCN, however, which could not be explained.     

Single-source impact analysis using three-dimensional air quality models

Isolating the effects of an individual emissions source on secondary air pollutants such as ozone and some components of particulate matter must incorporate complex nonlinear processes, be sensitive to small emissions perturbations, and account for impacts that may occur hundreds of kilometers away. The ability to evaluate these impacts is becoming increasingly important for efficient air quality management. Here, as part of a recent compliance enforcement action for a violation of the Clean Air Act and as an evaluation of ozone response to single-source emissions plumes, two three-dimensional regional photochemical air quality models are used to assess the impact on ozone from approximately 2000 to 3000 excess t/month of nitrogen oxides emitted from a single power plant in Ohio. Periods in May, July, and August are evaluated. Two sensitivity methods are applied: the "brute-force" (B-F) method and the decoupled direct method (DDM). Using DDM, maximum 1-hr averaged ozone concentrations are found to increase by up to 1.8, 1.3, and 2.2 ppbv during May, July, and August episodes, respectively, and concentration increases greater than 0.5 ppbv occur in Ohio, Pennsylvania, Maryland, New York, West Virginia, Virginia, and North and South Carolina. B-F results for the August episode show a maximum 1-hr averaged ozone concentration increase of 2.3 ppbv. Significant localized decreases are also simulated, with a maximum of 3.6 ppbv in Ohio during the August episode and decreases of 0.50 ppbv and greater in Ohio, Pennsylvania, Maryland, West Virginia, and Virginia. Maximum increases are compared with maximum decreases for the August period using second-order DDM and are found, in aggregate, to be greater in magnitude by 42%. When evaluated during hours when ozone concentrations exceed 0.060 ppm, the maximum increases in ozone are higher than decreases by 82%. The spatial extent of ozone increase in both cases is about triple that of reduction.     

Community evacuation following a chlorine release, Mississippi

On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided.     

Surveillance for adverse health effects following a chemical release in west virginia

On 11 August 1985, a large inadvertent release occurred from a chemical manufacturing plant in Institute, West Virginia. The emission was related to overheating of a storage tank that contained chemicals for the production of aldicarb, a cholinesterase inhibiting pesticide. As a result of this emission, 136 persons were treated in five local emergency rooms, 29 of whom were hospitalized for one or more days, mostly for observation. No fatalities resulted. Interviews with treated persons and non-treated community residents confirmed that the health effects were transient and compatible with exposure to irritating vapors rather than with exposure to methyl isocyanate (a chemical used in the process) or to aldicarb. Only 5% of the treated persons and 5% of the community residents surveyed were adequately warned of the emission by the plant siren. Because persons in the nearby community are potentially vulnerable to chemical injury, we recommend the development of an improved warning system, a formal evacuation procedure, and other measures to limit exposure of persons in this area in the event of a future release.     

Mechanism and catalytic performance for direct dimethyl ether synthesis by CO2 hydrogenation over CuZnZr/ferrierite hybrid catalyst

Direct synthesis of dimethyl ether(DME) by CO_2 hydrogenation has been investigated over three hybrid catalysts prepared by different methods:co-precipitation,sol-gel,and solid grinding to produce mixed Cu,ZnO,ZrO_2 catalysts that were physically mixed with a commercial ferrierite(FER) zeolite.The catalysts were characterized by N_2 physisorption,X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),temperature programmed desorption of CO_2(CO_2-TPD),temperature programmed desorption of NH_3(NH_3-TPD),and temperature programmed H2 reduction(H_2-TPR).The results demonstrate that smaller CuO and Cu crystallite sizes resulting in better dispersion of the active phases,higher surface area,and lower reduction temperature are all favorable for catalytic activity.The reaction mechanism has been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS).Methanol appears to be formed via the bidentate-formate(b-HCOO) species undergoing stepwise hydrogenation,while DME formation occurs from methanol dehydration and reaction of two surface methoxy groups.     

Integration of modeling,monitoring and laboratory observation to determine reasons for air quality violations

An attempt was made to explain ambient air quality violations in the vicinity of industrial plants. Micrometeorology, diffusion calculaations, ambient readings, and plant engineering data are all taken into consideration to ascertain whether the plant is or is not the principal offender.Scrutiny of hi-vol filters using scanning electron microscopy for particle size analysis and particle chemical make-up as an assessment technique is also described.Case histories using the above analytical techniques are discussed.Presented at the 16th National Conference on Energy and the Environment, May 23, 1979