On-board monitoring (OBM) for heavy-duty vehicle emissions in China: Regulations, early-stage evaluation and policy recommendations.

The latest China VI emission standard has introduced a remote monitoring rule for regulating in-use emissions of heavy-duty diesel vehicles (HDDVs). Real-time data regarding engine and aftertreatment operating conditions and tailpipe nitrogen oxides (NOx) concentrations are required to be collected through electronic control unit and on-board NOx sensors by vehicle original equipment manufacturers (OEMs), and then transmitted to environmental authorities. Beijing has developed a local standard that requires OEMs to design China VI-like on-board monitoring (OBM) systems for new China V HDDVs since September 2018. Additionally, Beijing has been a pioneer in retrofitting in-use China IV and China V HDDVs with OBM systems since 2017. This paper contains a timely technical and policy assessment for the state-of-the-art OBM programs in China with a focus on the recent progress in Beijing. Both OEM-performed and retrofitted OBM data were collected from a fleet of OBM-instrumented vehicles. First, our assessment shows high data integrity and quality of OEM-performed OBM systems. In contrast, a considerable fraction of HDDVs equipped with retrofitted OBM systems did not completely report NOx concentrations, intake mass air flow and other parameters. Next, eight OBM-instrumented HDDVs were tested on road by portable emissions measurement systems (PEMSs) to examine the reliability of sensor-based NOx concentrations. The majority (6 of 8) shows a good agreement between OBM and PEMS results with an average relative error of approximately -15%. Furthermore, calculation of NOx mass emissions, inter-trip variability, and alternative methods of enforcing in-use emissions management (e.g., to develop concentration metric-based emission limits) are discussed. This early-stage assessment suggests the OBM approach has the potential to play a central role in in-use emission inspections for HDDVs in China. The regulatory agency should focus more attention to the data integrity and the reliability of NOx sensors by developing effective verification processes.

A new approach of electrochemical etching fabrication based on drop-off-delay control.

W-Pt micro-nano-thermocouple is a brand new sensor for intracellular temperature measurement. As a nanodevice, it is based on the electrochemical etching method of which the shape is directly related to the performance. Although much research has been done on how to control the shape of the tungsten tip through electrochemical etching method, preparing different shapes requires different fabrication methods. In this article, we proposed a flexible and general control method which can fit all the fabrication methods by merely modifying the software. Moreover, this method based on drop-off-delay time control is capable of controlling the duration of the electrochemical reaction during the final formation of the tungsten tip. Based on this method, the cone angle can be set to any value from 5° to 30° with the radius of curvature maintaining from 2 nm to 5 nm. Additionally, the sophisticated fabrication of W-Pt micro-nano-thermocouple was designed to be automatically completed by three workshops in batches. The efficiency and uniformity of W-Pt micro-nano-thermocouple fabrication were well improved.

Real-time Temperature Measurements of HMEC-1 Cells during Inflammation Production and Repair detected by Wireless Thermometry.

Cell inflammation process is reflected through real-time in situ cellular temperature changes. METHODS: A wireless thermometry system for in situ cellular temperature measurements was used in an incubator to detect the HMEC-1 cellular temperature under lipopolysaccharide inflammation production and norepinephrine for inflammation repair. Combining the changes in cell viability, inflammatory factor levels and ATP content caused by different lipopolysaccharide or norepinephrine doses, an obvious inflammatory response and repair effect was obtained. Temperature variations were correlated with ATP content. RESULTS: An obvious inflammatory response with a lipopolysaccharide concentration of 0.1 mg/L and an optimal repair effect with 1 µM norepinephrine were obtained. The relationship between temperature changes and ATP content were quite different during the production of inflammation in HMEC-1 cells, having an approximately linear relationship, while under conditions of inflammation repair in HMEC-1 cells, there was an obvious nonlinear relationship. CONCLUSION: During cell damage, cell thermogenesis has a linear correlation with intracellular energy. While during cell repair, there is a gradual saturation relationship between the temperature (small range) and ATP, which may be because the thermogenesis capacity of the cell is enhanced compared to conditions during cell energy storage. Additionally, there is an optimal drug concentration for cell action during cell injury and cell repair, which is not dose-dependent. SIGNIFICANCE: Whether in inflammation production or treatment, there is an optimal drug concentration. The relationship between cell thermogenesis and intracellular energy reserves is related to cell processes. Quick analysis of the energy changes in different physiological process can be realized.

Validation of temporal and spatial consistency of facility- and speed-specific vehicle-specific power distributions for emission estimation: A case study in Beijing, China.

Vehicle-specific power (VSP) has been found to be highly correlated with vehicle emissions. It is used in many studies on emission modeling such as the MOVES (Motor Vehicle Emissions Simulator) model. The existing studies develop specific VSP distributions (or OpMode distribution in MOVES) for different road types and various average speeds to represent the vehicle operating modes on road. However, it is still not clear if the facility- and speed-specific VSP distributions are consistent temporally and spatially. For instance, is it necessary to update periodically the database of the VSP distributions in the emission model? Are the VSP distributions developed in the city central business district (CBD) area applicable to its suburb area? In this context, this study examined the temporal and spatial consistency of the facility- and speed-specific VSP distributions in Beijing. The VSP distributions in different years and in different areas are developed, based on real-world vehicle activity data. The root mean square error (RMSE) is employed to quantify the difference between the VSP distributions. The maximum differences of the VSP distributions between different years and between different areas are approximately 20% of that between different road types. The analysis of the carbon dioxide (CO2) emission factor indicates that the temporal and spatial differences of the VSP distributions have no significant impact on vehicle emission estimation, with relative error of less than 3%. IMPLICATIONS: The temporal and spatial differences have no significant impact on the development of the facility- and speed-specific VSP distributions for the vehicle emission estimation. The database of the specific VSP distributions in the VSP-based emission models can maintain in terms of time. Thus, it is unnecessary to update the database regularly, and it is reliable to use the history vehicle activity data to forecast the emissions in the future. In one city, the areas with less data can still develop accurate VSP distributions based on better data from other areas.