Emissions During and Real-world Frequency of Heavy-duty Diesel Particulate Filter Regeneration.

Recent tightening of particulate matter (PM) emission standards for heavy-duty engines has spurred the widespread adoption of diesel particulate filters (DPFs), which need to be regenerated periodically to remove trapped PM. The total impact of DPFs therefore depends not only on their filtering efficiency during normal operation, but also on the emissions during and the frequency of regeneration events. We performed active (parked and driving) and passive regenerations on two heavy-duty diesel vehicles (HDDVs), and report the chemical composition of emissions during these events, as well as the efficiency with which trapped PM is converted to gas-phase products. We also collected activity data from 85 HDDVs to determine how often regeneration occurs during real-world operation. PM emitted during regeneration ranged from 0.2 to 16.3 g, and the average time and distance between real-world active regenerations was 28.0 h and 599 miles. These results indicate that regeneration of real-world DPFs does not substantially offset the reduction of PM by DPFs during normal operation. The broad ranges of regeneration frequency per truck (3-100 h and 23-4078 miles) underscore the challenges in designing engines and associated aftertreatments that reduce emissions for all real-world duty cycles.

Total Particle Number Emissions from Modern Diesel, Natural Gas, and Hybrid Heavy-Duty Vehicles During On-Road Operation.

Particle emissions from heavy-duty vehicles (HDVs) have significant environmental and public health impacts. This study measured total particle number emission factors (PNEFs) from six newly certified HDVs powered by diesel and compressed natural gas totaling over 6800 miles of on-road operation in California. Distance-, fuel- and work-based PNEFs were calculated for each vehicle. Distance-based PNEFs of vehicles equipped with original equipment manufacturer (OEM) diesel particulate filters (DPFs) in this study have decreased by 355-3200 times compared to a previous retrofit DPF dynamometer study. Fuel-based PNEFs were consistent with previous studies measuring plume exhaust in the ambient air. Meanwhile, on-road PNEF shows route and technology dependence. For vehicles with OEM DPFs and Selective Catalytic Reduction Systems, PNEFs under highway driving (i.e., 3.34 × 1012 to 2.29 × 1013 particles/mile) were larger than those measured on urban and drayage routes (i.e., 5.06 × 1011 to 1.31 × 1013 particles/mile). This is likely because a significant amount of nucleation mode volatile particles were formed when the DPF outlet temperature reached a critical value, usually over 310 °C, which was commonly achieved when vehicle speed sustained over 45 mph. A model year 2013 diesel HDV produced approximately 10 times higher PNEFs during DPF active regeneration events than nonactive regeneration.

Measuring Particulate Emissions of Light Duty Passenger Vehicles Using Integrated Particle Size Distribution (IPSD).

The California Air Resources Board (ARB) adopted the low emission vehicle (LEV) III particulate matter (PM) standards in January 2012, which require, among other limits, vehicles to meet 1 mg/mi over the federal test procedure (FTP). One possible alternative measurement approach evaluated to support the implementation of the LEV III standards is integrated particle size distribution (IPSD), which reports real-time PM mass using size distribution and effective density. The IPSD method was evaluated using TSI's engine exhaust particle sizer (EEPS, 5.6-560 nm) and gravimetric filter data from more than 250 tests and 34 vehicles at ARB's Haagen-Smit Laboratory (HSL). IPSD mass was persistently lower than gravimetric mass by 56-75% over the FTP tests and by 81-84% over the supplemental FTP (US06) tests. Strong covariance between the methods suggests test-to-test variability originates from actual vehicle emission differences rather than measurement accuracy, where IPSD offered no statistical improvement over gravimetric measurement variability.

Criteria pollutant and greenhouse gas emissions from cargo handling equipment operating at the Ports of Los Angeles and Long Beach.

This study reports in-use emissions from eight pieces of diesel or natural gas cargo handling equipment (CHE) moving containerized freight at the Ports of Los Angeles and Long Beach. Equipment had engines certified to the legacy on-road model year (MY) 2010 or the off-road Tier 3, Tier 4 Interim, or Tier 4 Final emission standards. Overall, load factors were about half of the values in the California Air Resources Board's (CARB) current CHE emissions inventory, oxides of nitrogen (NOx) emissions were 2.7 times higher than certification standards, and tailpipe-emitted fine particulate matter (PM2.5) emissions were 2.2 times higher than certification standards. This is yet another study, the first dedicated to in-use operations by CHE at a large commercial seaport, showing elevated in-use emissions from combustion-powered mobile sources compared to certification levels. These results underscore the need to perform routine surveillance emissions testing of any off-road mobile source fleet when developing emission inventories and air quality programs for any jurisdiction worldwide. The Energy Economy Ratio (EER) - or ratio of increased efficiency from converting combustion to zero-emission battery-electric equipment - ranged from 2.8 to 3.7, which highlights potential energy savings and therefore greenhouse gas benefits of transitioning CHE and other freight sectors to zero-emission technologies.

How do particle number, surface area, and mass correlate with toxicity of diesel particle emissions as measured in chemical and cellular assays?

Increasingly stringent particulate matter (PM) emission standards have brought forth engine design improvements, cleaner-burning fuels, and aftertreatment technologies. Reductions in tailpipe PM mass have concomitantly reduced accumulation-mode particle emissions. However, some strategies promote the emission of nucleation-mode particles, which are typically quantified on a number (PN) basis. We previously demonstrated that PN emissions from heavy-duty diesel vehicles equipped with various aftertreatment systems were inversely correlated, and gravimetric PM mass was positively correlated, with two in vitro assays. This present work expands on the analysis of PM mass and PN with in vitro assays to also include four additional PM metrics: suspended PM mass, active particle surface area, aggregate particle surface area, and accumulation-mode particle number. This new analysis shows that like gravimetric PM mass, suspended particle mass and accumulation mode particle number are well correlated with dithiothreitol consumption rate (DTT) and macrophage reactive oxygen species consumption rate (ROS) assays (R2 = 0.61-0.96). Data suggest that PM mass emissions dominated by nucleation-mode particles induce equal or slightly greater toxicity compared to PM mass dominated by accumulation-mode particles. Data also show that among all PM metrics, those used for regulating PM in the United States and Europe, namely gravimetric mass and solid PN are overall most correlated with in vitro toxicity. Moreover, continued exploration of alternative, low-cost, and more appropriate PM metrics is warranted to better understand the reproducibility of these findings on other engine applications, fuel types, and aftertreatment platforms.

Real-time particulate emissions rates from active and passive heavy-duty diesel particulate filter regeneration.

Periodic regeneration is required to clean the diesel particulate filter (DPF) of heavy-duty diesel vehicle. In this study we analyze real-time particulate matter (PM) mass, particle number, and black carbon emissions during steady state driving active and passive diesel particulate filter (DPF) regenerations on a heavy-duty chassis dynamometer. Regeneration PM emissions were dominated by particles with count median diameter<100nm, with the majority <50nm. Results indicate that vehicle activity during DPF loading significantly affects regeneration particulate emissions. Average PM emission rates (gPM/h) from the 2010 MY vehicle were higher than the 2007 MY vehicle during all regeneration conditions in this study. Sequential forced-active regenerations resulted in reduced particulate mass emissions, but not in reduced particle number emissions, suggesting incomplete stored PM removal or effects of after-treatment fuel injection. Black carbon emission factors (EFBC) were 3.4 and 21 times larger during driving-active regeneration than during a 50 mph steady state cruise with a recently regenerated DPF for the 2007 and 2010 MY vehicle, respectively. Real-time PM emissions rates were lower during passive regeneration of the 2010 MY DPF, suggesting more modern passive regeneration technologies reduce total on-road particulate and ultrafine particulate emissions.

Deriving fuel-based emission factor thresholds to interpret heavy-duty vehicle roadside plume measurements.

Remote sensing devices have been used for decades to measure gaseous emissions from individual vehicles at the roadside. Systems have also been developed that entrain diluted exhaust and can also measure particulate matter (PM) emissions. In 2015, the California Air Resources Board (CARB) reported that 8% of in-field diesel particulate filters (DPF) on heavy-duty (HD) vehicles were malfunctioning and emitted about 70% of total diesel PM emissions from the DPF-equipped fleet. A new high-emitter problem in the heavy-duty vehicle fleet had emerged. Roadside exhaust plume measurements reflect a snapshot of real-world operation, typically lasting several seconds. In order to relate roadside plume measurements to laboratory emission tests, we analyzed carbon dioxide (CO2), oxides of nitrogen (NOX), and PM emissions collected from four HD vehicles during several driving cycles on a chassis dynamometer. We examined the fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power. Our analysis suggests that a typical HD vehicle will exceed the model year (MY) 2010 emission standards (of 0.2 g NOX/bhp-hr and 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NOX/kg fuel and 0.11 g PM/kg using the roadside plume measurement approach. Reported limits correspond to 99% confidence levels, which were calculated using the detection uncertainty of emissions analyzers, accuracy of vehicle power calculations, and actual emissions variability of fixed operational parameters. The PM threshold was determined for acceleration events between 0.47 and 1.4 mph/sec only, and the NOX threshold was derived from measurements where after-treatment temperature was above 200°C. Anticipating a growing interest in real-world driving emissions, widespread implementation of roadside exhaust plume measurements as a compliment to in-use vehicle programs may benefit from expanding this analysis to a larger sample of in-use HD vehicles. IMPLICATIONS: Regulatory agencies, civil society, and the public at large have a growing interest in vehicle emission compliance in the real world. Leveraging roadside plume measurements to identify vehicles with malfunctioning emission control systems is emerging as a viable new and useful method to assess in-use performance. This work proposes fuel-based emission factor thresholds for PM and NOx that signify exceedances of emission standards on a work-specific basis by analyzing real-time emissions in the laboratory. These thresholds could be used to prescreen vehicles before roadside enforcement inspection or other inquiry, enhance and further develop emission inventories, and potentially develop new requirements for heavy-duty inspection and maintenance (I/M) programs, including but not limited to identifying vehicles for further testing.

La fundamentación médico legal / The legal medical foundation

Resumen:La Fundamentación, es el apartado del dictamen médico legal, donde el médico forense plasma, de forma clara, precisa y detallada, los motivos que sustentan su criterio para emitir las conclusiones. Ésta, es la base de la pericia médico legal, dado que se exponen todos los elementos de juicio disponibles al momento de realizar un peritaje y le permite a la Autoridad Judicial darle o restarle validez a la pericia médico legal, como elemento de prueba.

Abstract:The foundation is the legal opinion of the medical section, where the coroner plasma, a clear, accurate and detailed the reasons that support your judgment to make findings. This is the basis of forensic expertise, since all available evidence when making an expertise and allows the Judicial Authority or subtract give validity to the forensic expertise as evidence are presented.

Aplicación de criterios médico legales en la relación de causalidad / Application of legal medical criteria on causation

El establecimiento de la relación de causalidad representa uno de los elementos más importantes en la valoración del daño corporal, esto porque a partir de ella sentamos la base de la pericia médico forense, además se pone en conocimiento de la Autoridad Judicial los elementos suficientes para determinar la causa y gravedad de una lesión, así como el menoscabo en la integridad psicofísica del evaluado. La presente revisión pretende exponer diferentes criterios médico legales aplicables a la realización del nexo de causalidad, aplicables no solo a las lesiones traumáticas sino también a las alteraciones causadas por procesos patológicos naturales.

Establishing causation is one of the most important elements in the assessment of body damage, this because from it sat the basis of forensic medical expertise also gets sufficient information to the attention of the Judicial Authority to determine the cause and severity of injury and impairment of the psychophysical integrity evaluated. The present review aims to present different legal medical criteria for the realization of the causal link, applicable not only traumatic injuries but also to changes caused by natural disease processes.

Estimación del tiempo de evolución de las excoriaciones, basado en el análisis histológico / Estimated time evolution of excoriations, based on histological analysis

Las excoriaciones, desde el punto de vista médico legal, tienen un gran valor analítico porque permiten establecer criterios de gran relevancia para la buena administración de la justicia. Uno de ellos es la correcta interpretación en relación al tiempo de evolución, que puede determinar la dirección que tome un caso, sin embargo, en muchas ocasiones esta estimación se hace de manera empírica. Dada la necesidad de tener elementos objetivos para realizar este tipo de estimaciones, es necesario realizar un análisis micro y macroscópico de las excoriaciones que permita establecer cuales son las características primordiales a estudiar si se desea hacer una valoración más detallada del tiempo de evolución de estas lesiones.

Chafing from the forensic point of view, have a great analytical value because they allow to establish criteria of great importance to the proper administration of justice. One of them is the correct interpretation in relation to time of evolution, which can determine the direction to take a case, however, in many cases this estimate is made empirically. Given the need for objective factors such estimates, it is necessary to perform a macroscopic and micro abrasions in order to establish which are the key features to consider if you want to make a more detailed assessment of the evolution of these lesions analysis.

Utilización de los productos de desechos de las industrias agrícolas y de alimentos en la nutrición animal / Utilization of the waste products of the agricultural industry and the food in the animal nutrition

Se llevó a cabo un estudio para probar el valor nutritivo de los productos de desecho generados en Panamá. Las veinticinco (25) terneras Holstein rumiantes, de edades entre 14 y 22 semanas, fueron asignadas al azar, por peso, a uno de los siguientes cinco (5) tratamientos: 1) Ración estandar-maíz (25 por ciento), heno (33 por ciento), arroz pulidura (20 por ciento) y pulpa cítrica (20 por ciento); 2) Control doméstico-heno (100 por ciento); 3) Control de harina de cáscara de camarones-maíz (30 por ciento), heno (25 por ciento), pulpa cítrica (28 por ciento) y harina de cáscara de camarones (14 por ciento); 4) Control de suero de leche-heno (35 por ciento); y 5) la ración experimental-heno (25 por ciento), pulpa cítrica (22 por ciento), suero de la leche desecado (35 por ciento), harina de cáscara de camarones (14 por ciento) y bagazo de caña de azúcar (6 por ciento). Las raciones 1, 3, 4 y 5 fueron formuladas para satisfacer el (75 por ciento) de nutrientes recomendados por el Consejo Nacional de Investigación (NCR). El estudio duró 33 días y los alimentos y el agua fueron sunimistrados ad libitum. La ganancia promedio de peso corporal para las raciones 1 a 5 fue de 0.070, 0.528, 0.749, 0.702 y 0.846 kg/día/ternera, respectivamente. Los resultados demostraron que la ración experimental fue la mejor y produjo una ganancia promedio en el peso corporal de casi (45 por ciento) con respecto a la ración local N§ 2. Las terneras, que recibieron el suero de la leche, presentaron diarrea, mientras que aquellas que recibieron la ración control con la harina de cáscara de camarones tuvieron estreñimiento. Por otro lado, las terneras que recibieron la ración experimental tenían heces normales. Se concluye que se puede formular una ración adecuada para animales, que contenga exclusivamente los sub-productos o productos de desecho existentes en Panamá