Effects of injection and ignition timing of a large direct injection spark ignition engine fuelled with a hydrogen-CNG mixture on its operating conditions and emissions

The effects of ignition and fuel injection timing of an experimental 2-liter single cylinder direct injection spark ignition gaseous fuel engine were examined experimentally in this study. An online-prepared mixture of 10-40% hydrogen with compressed natural gas was injected at 8 bar into the cylinder during the intake stroke at 1500 rpm. Heat release rates, maximum indicated pressures, cycle-to-cycle variability, and gaseous emissions were compared for different settings. © The Authors, published by EDP Sciences, 2017

Cervical visual inspection with acetic acid (VIA) and oncogenic human papillomavirus screening in rural indigenous guatemalan women: Time to rethink VIA

Single-visit “screen-and-treat” strategies using visual inspection with acetic acid (VIA) and cryotherapy (liquid nitrous oxide ablation) in low-resource settings are commonly used to de-tect and treat precancerous lesions for cervical cancer prevention. This study compared VIA sensi-tivity and specificity in rural indigenous Guatemalan communities, to that of oncogenic human papillomavirus (HPV) testing for detection of precancerous changes, using cytology as the reference standard. Between 3–8 September 2017, trained nurses examined 222 women aged 23–58 years with VIA. Specimens for liquid-based cytology and HPV testing were obtained prior to VIA with a cyto-brush and transported in PreservCyt to a US clinical laboratory. VIA and HPV test sensitivities were assessed as proportions of women with abnormal cytology that had abnormal VIA or HPV results, respectively, and specificities, as proportions with normal cytology with normal VIA or negative HPV tests. Of 222 women, 18 (8.1%) had abnormal cytology (1 carcinoma in a participant who received VIA-based cryotherapy in 2015, 4 high-and 5 low-grade squamous intraepithelial lesions, and 8 atypical squamous cells of undetermined significance (ASCUS)). Excluding ASCUS, sensitivities of VIA and HPV were 20.0% and 100%, respectively. VIA-based screening may not be accepta-ble for detecting precancerous lesions, and field cryotherapy for preventing malignancy. The World Health Organization recommended in 2021 “…using HPV DNA detection as the primary screening test rather than VIA or cytology.”

N-butanol and isobutanol as alternatives to gasoline: Comparison of port fuel injector characteristics

The paper reports on an experimental investigation of the relationship between the pulse width of a gasoline engine port fuel injector and the quantity of the fuel injected when butanol is used as a fuel. Two isomers of butanol, n-butanol and isobutanol, are considered as potential candidates for renewable, locally produced fuels capable of serving as a drop-in replacement fuel for gasoline, as an alternative to ethanol which poses material compatibility and other drawbacks. While the injected quantity of fuel is typically a linear function of the time the injector coil is energized, the flow through the port fuel injector is complex, non ideal, and not necessarily laminar, and considering that butanol has much higher viscosity than gasoline, an experimental investigation was conducted. A production injector, coupled to a production fueling system, and driven by a pulse width generator was operated at various pulse lengths and frequencies, covering the range of engine rpm and loads on a car engine. The results suggest that at least at room temperature, the fueling rate remains to be a linear function of the pulse width for both n-butanol and isobutanol, and the volumes of fuel injected are comparable for gasoline and both butanol isomers

N-butanol and isobutanol as alternatives to gasoline: Comparison of port fuel injector characteristics

The paper reports on an experimental investigation of the relationship between the pulse width of a gasoline engine port fuel injector and the quantity of the fuel injected when butanol is used as a fuel. Two isomers of butanol, n-butanol and isobutanol, are considered as potential candidates for renewable, locally produced fuels capable of serving as a drop-in replacement fuel for gasoline, as an alternative to ethanol which poses material compatibility and other drawbacks. While the injected quantity of fuel is typically a linear function of the time the injector coil is energized, the flow through the port fuel injector is complex, non ideal, and not necessarily laminar, and considering that butanol has much higher viscosity than gasoline, an experimental investigation was conducted. A production injector, coupled to a production fueling system, and driven by a pulse width generator was operated at various pulse lengths and frequencies, covering the range of engine rpm and loads on a car engine. The results suggest that at least at room temperature, the fueling rate remains to be a linear function of the pulse width for both n-butanol and isobutanol, and the volumes of fuel injected are comparable for gasoline and both butanol isomers

Measurement of reed valve kinematics

The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed

Measurement of reed valve kinematics

The measurement of key kinematic parameters of a reed valve movement is necessary for the further development of the reed valve system. These parameters are dependent on the geometry and material properties of the valve. As they directly affect the quantity of air flowing around the valve, a simple and easy to implement measurement of various valve configuration based on the air flow has been devised and is described in this paper, along with its technical parameters and drawbacks when evaluating reed valves used in reciprocating air compressors. Results are presented for a specimen of a compressor under examination. All kinematic parameters, and timing of the opening and closing of the valve, obtained from the measurement are presented and discussed