Original Index Research Articles

The reporting of climate-related information by CSR leaders in Poland: a climate-related disclosures index

The article measures the scope of reporting climate-related information by companies considered CSR leaders in Poland. An original tool is employed for that purpose: a climate-related disclosures index. First, a critical comparative analysis was performed of climate-related disclosure initiatives (regulations, guidelines, standards) to pinpoint the key and commonly required disclosures. Next, an original index of climate-related disclosures was designed. It helped compute index values for 20 companies perceived as Poland’s CSR leaders. Non-financial reports available in the public domain were analysed for that purpose. The study showed that virtually all climate-related disclosure initiatives implement, to a greater or lesser extent, the TCFD recommendations, which were also embedded in the developed index covering 18 indicators. The total index value (ranging from 0 to 1) for the analysed companies was 0.51 with the median of 0.42. The index demonstrates that companies named CSR leaders in Poland do not display high awareness of climate change.

The hemoglobin, albumin, lymphocyte, and platelet (HALP) is a potent indicator for the prognosis in hemodialysis patients.

The hemoglobin, albumin, lymphocyte, and platelet (HALP) values were marked as a original index of general nutritional and inflammatory conditions. The purpose of this investigation was to evaluate the potential relationship between HALP and prognosis in hemodialysis (HD) patients. Patients with maintenance HD from multiple dialysis centers in China were retrospectively analyzed. The primary poor outcome were cardiovascular disease (CVD) and all-cause death. The computational equation of HALP values as the follows: hemoglobin (g/L) × albumin (g/L) × lymphocytes (/L)/ platelets (/L). All participants were divided into Tertile 1, Tertile 2, and Tertile 3 according to the tertiles of baseline HALP values. The Kaplan-Meier curve and the Cox regression was done to figure out the relationship about HALP and adverse outcomes. The restricted cubic splines further identified the possible associations. The time-dependent receiver operating characteristic curve and C-index were implemented for evaluate the predictive values of the HALP composite model. There were 4796 patients incorporate into ultimate study. Compared with patients in Tertile 1, patients in Tertile 3 had an lower risk of all-cause mortality [hazard ratios = 0.66, 95% confidence intervals: 0.49-0.86, P = .007] and CVD mortality [sub-distribution hazard ratio = 0.51, 95% confidence intervals: 0.34-0.80, P = .005]. The composite model with the supplement of HALP outperformed the traditional factor model in the time-dependent receiver operating characteristic curve. High HALP values at baseline are related to a diminished risk of CVD death and all-cause death in HD patients. HALP is a novel and potent index for the prognosis of HD patients.

Evaluating the prebiotic effect of oligosaccharides on gut microbiome wellness using in vitro fecal fermentation

We previously proposed the Gut Microbiome Wellness Index (GMWI), a predictor of disease presence based on a gut microbiome taxonomic profile. As an application of this index for food science research, we applied GMWI as a quantitative tool for measuring the prebiotic effect of oligosaccharides. Mainly, in an in vitro anaerobic batch fermentation system, fructooligosaccharides (FOS), galactooligosaccharides (GOS), xylooligosaccharides (XOS), inulin (IN), and 2’-fucosyllactose (2FL), were mixed separately with fecal samples obtained from healthy adult volunteers. To find out how 24 h prebiotic fermentation influenced the GMWI values in their respective microbial communities, changes in species-level relative abundances were analyzed in the five prebiotics groups, as well as in two control groups (no substrate addition at 0 h and for 24 h). The GMWI of fecal microbiomes treated with any of the five prebiotics (IN (0.48 ± 0.06) > FOS (0.47 ± 0.03) > XOS (0.33 ± 0.02) > GOS (0.26 ± 0.02) > 2FL (0.16 ± 0.06)) were positive, which indicates an increase of relative abundances of microbial species previously found to be associated with a healthy, disease-free state. In contrast, the GMWI of samples without substrate addition for 24 h (–0.60 ± 0.05) reflected a non-healthy, disease-harboring microbiome state. Compared to the original prebiotic index (PI) and α-diversity metrics, GMWI provides a more data-driven, evidence-based indexing system for evaluating the prebiotic effect of food components. This study demonstrates how GMWI can be applied as a novel PI in dietary intervention studies, with wider implications for designing personalized diets based on their impact on gut microbiome wellness.

Adapted Water Quality Indices: Limitations and Potential for Water Quality Monitoring in Africa

A Water Quality Index (WQI) is a tool that describes the overall water quality by combining complex and technical water quality information into a single meaningful unitless numerical value. WQIs predict water quality since they reflect the impact of multiple Water Quality Parameters (WQPs) and allow for spatial-temporal comparison of water quality status. Most African countries employ adapted WQIs by modifying the original index (or indices) and propose their concepts for evaluating the quality of surface and groundwater, which is normally accompanied by irregularities. The current review examined the process(es) involved in WQI modifications for monitoring water quality in Africa, explored associated limitations, and suggested areas for improvement. A review of 42 research articles from five databases in the last ten years (2012–2022) was conducted. The findings indicated Weighted Arithmetic (WAWQI) and the Canadian Council of Ministers of Environment (CCMEWQI) as the most adapted WQIs. However, several limitations were encountered in WQI developmental steps, mainly in parameter selection and classification schemes used for the final index value. Incorporation of biological parameters, use of less subjective statistical methods in parameter selection, and logical linguistic descriptions in classification schemes were some recommendations for remedying the limitations to register the full potential of adapted WQIs for water quality monitoring in Africa.

Research on the Teaching Quality Evaluation System of Ideological and Political Theories Teaching in All Courses Based on Analytic Hierarchy Process

This paper builds the teaching quality evaluation system of ideological and political theories teaching in all courses based on analytic hierarchy process from the perspectives of students, teachers, experts, and employers. First, the original indexes of ideological and political teaching quality evaluation are extracted from the core elements of the evaluation of four types of evaluation mainstay, the evaluation index system is built by principal component analysis in order to eliminate the influence of the correlation among the original indexes, secondly, the importance of various indexes scored by Wenzhou university education and teaching experts as basis, the analytic hierarchy process is used to build model and determine the weight of evaluation indexes. This paper can provide scientific and reasonable references for the teaching quality evaluation of the quality of ideological and political theories teaching in all courses for vocational colleges and other types of universities.

Sustainability Evaluation of Chinese Capital Cities Based on Urban Geographic Environment Index

Environmental assessments are important tasks for the long-term, sustainable development of cities. With the rapid urbanization in China, it is crucial to establish a City Sustainability Index (CSI) and evaluate the environmental conditions in major cities. However, most of the existing major sustainability indices/indicators are not able to assess cities at diverse levels of development using common axes of evaluation. In this work, we incorporate urban built-up areas extracted from high-resolution remote sensing images as indicators to measure the degree of urban development in city sustainability evaluation and propose a comprehensive index, i.e., the Urban Geographic Environment Index (UGEI). In order to eliminate the impact of urban development levels, UGEI mainly consists of area-averaged indices which are calculated from original indices and urban built-up areas. We adopt a comprehensive weighting method by using the analytic hierarchy process (AHP) method to weigh the high-level indicators and using the entropy weighting method to weigh low-level indicators. We evaluate the environmental conditions of 30 China’s provincial capitals from the aspects of pressure, state, response, and overall status. In addition, we analyze how diverse types of indicators affect the values of UGEIs. The major findings are as follows: (1) About half of the provincial capitals in China have poor sustainability in environmental conditions, and more environmental protection measures should be taken in developing cities; (2) the environmental conditions of the provincial capitals in China present a four-region distribution pattern, namely, the northeastern coastal region, northwest inland region, southwest region, and southeast region; (3) and indices based on urban built-up extents can be common axes of evaluation for cities at diverse levels of development. The proposed UGEI can serve as an effective and reliable index for sustainability evaluation in environmental conditions.

Coffee Production and Geographical Indications (GI): An Analysis of the World Panorama and the Brazilian Reality

Coffee cultivation is of great importance in the world economy. Due to consumers' demand for products with quality and geographic certification, the topic is relevant. The research objective is to portray the international and Brazilian scenario of the coffee production chain, based on production and Geographical Indications (GIs) for the product. The research is classified as exploratory and descriptive in relation to the approach, and as bibliographical and documental in relation to the means of investigation. It was found that the world's largest coffee producers are Brazil, Vietnam, Colombia, and Indonesia. There was a reduction in world production for the 2021/22 crop, due to the low production of arabica coffee in Brazil, but for the 2022/23 crop, an increase in this production is estimated. Most coffee-producing countries follow specific legislation to protect Geographical Indications and others protect them through trademarks. In Brazil, the definition of GI is explained by its species, Indication of Origin (IO), and Denomination of Origin (DO). Brazil is the second with the highest number of GIs for coffee in the world. El Salvador has a GI that represents the entire coffee value chain. Indonesia is the country with the highest number of GIs for coffee in the world and has state support for its promotion. Given this scenario, there is a need to develop public policies aimed at this product. It is indicated for future research the study of these policies and the performance of bodies responsible for the consolidation of GIs in their respective countries.

From Dynamite Hill to The Black Power Mixtape: Angela Davis on the Violence/Nonviolence Binary and the Mediation of Black Political Thought

This essay explores the archive of a 1971 interview of Angela Davis by Swedish journalist Bo Holmström—recorded in Santa Clara County Jail where Davis awaited trial—to examine the relationship between Black radical thought and its social and intellectual mediation, especially when it comes to questions of violence versus nonviolence. Where Holmström invokes the “violence/nonviolence” binary in the interview, Davis pointedly resists its distortions, restoring the record of contemporary and historical conditions of racial terror that both necessitate and criminalize Black self-defense. Decades later, the interview was filtered through the violence/nonviolence binary in editing for the acclaimed 2011 documentary, The Black Power Mixtape 1967-1975, with Davis’s wider conversation with Holmström not only abridged but remixed into a shorter exchange on armed self-defense. Studying the interview from its conditions of possibility through its later remixing, and reading it together with her opening defense statement (1972) and later speeches and writings, the essay excavates and explicates Davis’s original theoretical interventions and indexes a cluster of forces that mediate Black radical thought, Black women’s radical thought more specifically, and prison texts. The final section historicizes Davis’s theorization of the spatial and relational contexts of Black self-defense in Dynamite Hill, Alabama, and in California, and contends that her incisive interventions into the violence/nonviolence binary in 1971 remain critical here and now.

What determines governments’ COVID-19 response policies?: examining national level policy and transnational factors

ABSTRACT This study examines to what extent the respective countries’ global pandemic response policies are determined by national-level policy factors (governance factor and public spending) and transnational factors (migrant & foreign direct investment-in-flow). This research employs Oxford University’s COVID-19 Government Response Index (GRI) to reflect upon 147 countries’ response types and extents against the global pandemic. This GRI consists of a containment and health index, an economic support index, and the original stringency index. By utilizing multiple regression analysis, this study assesses the effects of domestic and transnational factors on the government’s stringency level. The results reveal that the governance factor turned out to have a significant positive effect. Domestic and transnational factors show partial and inconsistent effects. This study also discloses the difference in governments’ pandemic responses by continent. This study contributes to refining conventional domestic public administration theory and exploring transnational public administration theory reflected in governments’ COVID-19 responses.

서울형 주택 실거래 가격지수의 적합성 검증에 관한 연구

As an indicator of housing price trends, the housing price index should have both accuracy and timeliness. This study aimed to validate the statistical reliability, stability of the Seoul actual price index for apartments developed by the Seoul Metropolitan Government, and its conformity on shortening of the publication time difference from 45 days to 15 to secure the timeliness of the index. The result showed that Seoul actual price index for apartments by building ages and housing areas have statistical reliability and stability throughout all detailed subtypes. Also, the additional analysis on the change in the index after reflecting cancelled transactions showed that there was insignificant difference between the original index and the index reflecting cancelled transactions. Therefore, this study empirically proved that Seoul actual price index for apartments can secure timeliness by collecting and analyzing data on the basis of date of registration without any distortion of the housing market.

The Role of Carbamoyl Phosphate Synthetase 1 as a Prognostic Biomarker in Patients With Acetaminophen-induced Acute Liver Failure

Carbamoyl phosphate synthetase 1 (CPS1) is a highly abundant mitochondrial urea cycle enzyme that is expressed primarily in hepatocytes. CPS1 is constitutively and physiologically secreted into bile but is released into the bloodstream upon acute liver injury (ALI). Given its abundance and known short half-life, we tested the hypothesis that it may serve as a prognostic serum biomarker in the setting of acute liver failure (ALF). CPS1 levels were determined using enzyme-linked immunosorbent assay and immunoblotting of sera collected by the ALF Study Group (ALFSG) from patients with ALI and ALF (103 patients with acetaminophen and 167 non-acetaminophen ALF etiologies). A total of 764 serum samples were examined. The inclusion of CPS1 was compared with the original ALFSG Prognostic Index by area under the receiver operating characteristic curve analysis. CPS1 values for acetaminophen-related patients were significantly higher than for non-acetaminophen patients (P < .0001). Acetaminophen-related patients who received a liver transplant or died within 21 days of hospitalization exhibited higher CPS1 levels than patients who spontaneously survived (P= .01). Logistic regression and area under the receiver operating characteristic analysis of CPS1 enzyme-linked immunosorbent assay values improved the accuracy of the ALFSG Prognostic Index, which performed better than the Model for End-Stage Liver Disease, in predicting 21-day transplant-free survival for acetaminophen- but not non-acetaminophen-related ALF. An increase of CPS1 but not alanine transaminase or aspartate transaminase, when comparing day 3 with day 1 levels was found in a higher percentage of acetaminophen transplanted/dead patients (P < .05). Serum CPS1 determination provides a new potential prognostic biomarker to assess patients with acetaminophen-induced ALF.

Data-Driven Evaluation of the Synergistic Development of Economic-Social-Environmental Benefits for the Logistics Industry

The receding globalization has reshaped the logistics industry, while the additional pressure of the COVID-19 pandemic has posed new difficulties and challenges as has the pressure towards sustainable development. Achieving the synergistic development of economic, social, and environmental benefits in the logistics industry is essential to achieving its high-quality development. Therefore, we propose a data-driven calculation, evaluation, and enhancement method for the synergistic development of the composite system of economic, social, and environmental benefits (ESE-B) of the logistics industry. Based on relevant data, the logistics industry ESE-B composite system sequential parametric index system is then constructed. The Z-score is applied to standardize the original index data without dimension, and a collaborative degree model of logistics industry ESE-B composite system is constructed to estimate the coordinated development among the subsystems of the logistics industry’s ESE-B system. The method is then applied to the development of the logistics industry in Anhui Province, China from 2011 to 2020. The results provide policy recommendations for the coordinated development of the logistics industry. This study provides theoretical and methodological support for the sustainable development aspects of the logistics industry.

Prognostic value of deep learning–based fibrosis quantification on chest CT in idiopathic pulmonary fibrosis

To investigate the prognostic value of deep learning (DL)-driven CT fibrosis quantification in idiopathic pulmonary fibrosis (IPF). Patients diagnosed with IPF who underwent nonenhanced chest CT and spirometry between 2005 and 2009 were retrospectively collected. Proportions of normal (CT-Norm%) and fibrotic lung volume (CT-Fib%) were calculated on CT using the DL software. The correlations of CT-Norm% and CT-Fib% with forced vital capacity (FVC) and diffusion capacity of carbon monoxide (DLCO) were evaluated. The multivariable-adjusted hazard ratios (HRs) of CT-Norm% and CT-Fib% for overall survival were calculated with clinical and physiologic variables as covariates using Cox regression. The feasibility of substituting CT-Norm% for DLCO in the GAP index was investigated using time-dependent areas under the receiver operating characteristic curve (TD-AUCs) at 3years. In total, 161 patients (median age [IQR], 68 [62-73] years; 104 men) were evaluated. CT-Norm% and CT-Fib% showed significant correlations with FVC (Pearson's r, 0.40 for CT-Norm% and - 0.37 for CT-Fib%; both p < 0.001) and DLCO (0.52 for CT-Norm% and - 0.46 for CT-Fib%; both p < 0.001). On multivariable Cox regression, both CT-Norm% and CT-Fib% were independent prognostic factors when adjusted to age, sex, smoking status, comorbid chronic diseases, FVC, and DLCO (HRs, 0.98 [95% CI 0.97-0.99; p < 0.001] for CT-Norm% at 3years and 1.03 [1.01-1.05; p = 0.01] for CT-Fib%). Substituting CT-Norm% for DLCO showed comparable discrimination to the original GAP index (TD-AUC, 0.82 [0.78-0.85] vs. 0.82 [0.79-0.86]; p = 0.75). CT-Norm% and CT-Fib% calculated using chest CT-based deep learning software were independent prognostic factors for overall survival in IPF. • Normal and fibrotic lung volume proportions were automatically calculated using commercial deep learning software from chest CT taken from 161 patients diagnosed with idiopathic pulmonary fibrosis. • CT-quantified volumetric parameters from commercial deep learning software were correlated with forced vital capacity (Pearson's r, 0.40 for normal and - 0.37 for fibrotic lung volume proportions) and diffusion capacity of carbon monoxide (Pearson's r, 0.52 and - 0.46, respectively). • Normal and fibrotic lung volume proportions (hazard ratios, 0.98 and 1.04; both p < 0.001) independently predicted overall survival when adjusted for clinical and physiologic variables.

Novel modified quantitative index for cone-beam CT assessment of medication-related osteonecrosis of the jaw - comparative analysis with original index

PurposeThe main research goal was to address the critical need for an objective and quantitative index to describe the nature and extent of radiographic features of medication-related osteonecrosis of the jaw (MRONJ) lesions and complement the descriptive radiographic interpretation of the lesion and its clinical assessment. Method and MaterialsA retrospective review of MRONJ patients assessed at our institution was performed to compare the Composite Radiographic Index (CRI), identified from a prior scoping review, with a proposed modification, the Modified CRI index (‘Mod-CRI’). The Mod-CRI index was weighted to assign a higher score for diffuse radiographic involvement of a given lesion, and delineated MRONJ lesions into those with ‘high’ and ‘low’ severity. Twenty-two MRONJ cases imaged with CBCT were retrospectively assessed with both CRI and Mod-CRI indices and the two indices were compared for their ability to quantitatively describe cone-beam computerized tomography (CBCT) radiographic features and complement the clinical staging of the MRONJ lesion. ResultsThere was a statistically significant association between increased clinical stage and higher mod-CRI score (p = 0.040).The Mod-CRI index sorted the patients who scored intermediate scores with the CRI (n = 15) into either the low (n = 8) or high categories (n = 7). ConclusionThe Mod-CRI index eliminated the ambiguous intermediate-category-scores in the previously published CRI index and provided greater clarity to the interpretation of a given index score. Adopting the Mod-CRI could improve MRONJ assessment and enhance communication between the radiologist and the clinician.

Inter-annual drought monitoring in northern mixed grasslands by a revised vegetation health index from historical Landsat imagery

Drought is defined as a natural phenomenon with comprehensive influences on ecosystems, economies, and the livelihood and health of people resident in the affected regions. Severe drought has affected the grassland ecosystem in the Canadian prairie region with increased frequency. Thus, it is essential to monitor the drought effects. With various temporal, spectral, and spatial resolutions, remote sensing data can detect vegetation's dynamic responses to drought. The objective of this study was to monitor inter-annual drought in the northern mixed grassland, over the last thirty-six years by using remote sensing approach through a revised vegetation health index (VHIr), which combined the vegetation condition index (VCI), the temperature condition index (TCI), and the dead fuel condition index (DCI) together. Historical Landsat imagery was explored to establish the VHIr and this index was tested in the Grasslands National Parks (GNP), a typical conserved northern mixed grasslands region. The results suggested that the VHIr can distinguish dry and wet years effectively and a VHIr map was able to depict the spatial distribution pattern of the drought severity. Compared with the original vegetation health index (VHI), VHIr was more correlated with the dead-to-green biomass ratio. Meanwhile, the spatial pattern indicated that the valley grasslands had relatively low drought sensitivity; the upland grasslands experienced severe to extreme drought severity during dry years, due to a large amount of dead vegetation existed; and the drought effect on sloped grasslands was due to relatively sparse vegetation cover. In addition, VHIr was significantly correlated with greenness and wetness components derived from the tasseled cap (K-T) transformation but the correlation coefficients (r) varied between dry and wet years and among different grassland landscapes. This study expanded our understanding of the spatial and temporal distribution of drought severity in the northern mixed grasslands, which can facilitate natural resource management in the arid and semi-arid regions.

Translation, Cultural Adaptation and Validation of Cardiff Acne Disability Index in Nepali Language.

Acne causes significant impairment in the quality of life of patients, but clinicians in Nepal lack a simple validated tool to measure the psychological side of acne. We planned to translate and validate Cardiff Acne Disability Index, a five item questionnaire into Nepali language to address this need. A linguistic translation with semantic equivalence to the original English language Cardiff Acne Disability Index was achieved through standard forward and backward translation into Nepali language. All eligible patients were requested to fill the Nepali translated version of both Cardiff Acne Disability Index and Dermatology Life Quality Index questionnaires. Reliability and validity of the newly translated questionnaire were established, based on statistical analyses of factor structure, item correlations and concurrent correlations. This validity study included 94 patients with male: female ratio of 1:3.27 and mean age 21.29 (±3.92) years. Reliability analysis revealed a Cronbach's alpha of .72 and mean inter item correlation coefficient of .337. A single factor was extracted on Principal Component Analysis explaining 48.40% of variance. A strong correlation of Cardiff Acne Disability Index scores to the Dermatology Life quality Index score (rs>.7) indicated good concurrent validity. The newly translated Nepali Cardiff Acne Disability Index is a valid tool to measure the impact of acne in Nepalese patients. This short and simple assessment tool will help clinicians understand the patient's perspective of her acne.

Hydrocarbon generation and retention potential of Chang 7 organic-rich shale in the Ordos Basin, China

This study investigates the hydrocarbon generation and retention potential of Chang 7 organic-rich shale, with an emphasis on the producibility of retained hydrocarbons, using a sample set chosen to represent a maturity spectrum of 0.54–0.9% R o and organic matter of type II and mixed type II–III. Based on the present-day hydrogen index (HI pd ), the sample sets were divided into three sections: Upper, Middle and Lower. The three sections have a high hydrocarbon generation potential, with an average original total organic carbon (TOC o ) content of 12.27, 3.10 and 5.13 wt%, of which 49.39, 23.62 and 49.86 wt% represents generative organic carbon (GOC), and an original hydrogen index (HI o ) of 581.27, 278.05 and 586.82 HC g −1 rock in the Upper, Middle, and Lower sections, respectively. The bulk of the analysed samples exhibited moderate–high oil saturation, yet the oil crossover effect was only observed in two organic-rich samples, indicating organic-rich shale-oil resource systems. The sorption capacity of organic matter controls oil retention in the Chang 7 shale system, where the oil saturation index increases with increasing maturity in the oil window until a maximum retention capacity of about 82–83 mgHC g −1 TOC is reached at a vitrinite reflectance of 0.8% and thereafter decreases with further maturity. Supplementary material: A detailed spreadsheet of the back-calculated original geochemical parameters using the mass-balance method of Jarvie (2012 a ) is available at https://doi.org/10.6084/m9.figshare.c.6387577

Event-Triggered Near-Optimal Control for Unknown Discrete-Time Nonlinear Systems Using Parallel Control.

This article uses parallel control to investigate the problem of event-triggered near-optimal control (ETNOC) for unknown discrete-time (DT) nonlinear systems. First, to achieve parallel control, an augmented nonlinear system (ANS) with an augmented performance index (API) is proposed to introduce the control input into the feedback system. The control stability relationship between the ANS and the original system is analyzed, and it is shown that, by choosing a proper API, optimal control of the ANS with the API can be seen as near-optimal control of the original system with the original performance index (OPI). Second, based on parallel control, a novel event-triggered scheme is proposed, and then a novel ETNOC method is developed using the time-triggered optimal value function of the ANS with the API. The control stability is proved, and an upper bound, which is related to the design parameter, is provided for the actual performance index in advance. Then, to implement the developed ETNOC method for unknown DT nonlinear systems, a novel online learning algorithm is developed without reconstructing unknown systems, and neural network (NN) and adaptive dynamic programming (ADP) techniques are employed in the developed algorithm. The convergence of the signals in the closed-loop system (CLS) is shown using the Lyapunov approach, and the assumption of boundedness of input dynamics is not required. Finally, two simulations justify the theoretical conjectures.

Restoration of sedimentary environment and geochemical features of deep marine Longmaxi shale and its significance for shale gas: A case study of the Dingshan area in the Sichuan Basin, South China

With the urgent need to increase shale gas production and reserves, deep shale gas has gradually become an important target for further exploration in China. However, there is still a lack in systematic research on the quality of different lithofacies types of shales in deep shale gas reservoirs. The overmature shales have a common problem, that is, the organic matter (OM) quality could not be clearly characterized by using conventional organic geochemical indicators, hindering the process of fine shale gas exploration. In this study, the deep marine Longmaxi (LMX) shale samples in the Dingshan area, southeastern Sichuan Basin were selected as a study case to investigate their lithofacies types, sedimentary environment and organic matter accumulation (OMA) mechanism, and restore the original OM attributes including original organic carbon content (TOCo) and original hydrogen index (HIo) for the different shale types to identify the favorable lithofacies for shale gas enrichment. The results show that the LMX shale can be divided into five different lithofacies, such as the OM-rich siliceous (RS) shale, OM-rich mixed (RM) shale, OM-lean siliceous (LS) shale, OM-lean mixed (LM) shale and OM-lean argillaceous (LA) shale, with a gradually decrease of their TOC contents. The TOC content of the LMX shale has a positive synergy with the indicators of paleoproductivity and redox conditions. However, since the studied area is close to the underwater highland with a high oxygen content in the bottom water and a great input of terrigenous debris, the OMA mainly depends on the level of high paleoproductivity. The analysis of sedimentary environment indicates that the OM amount and quality in various lithofacies shales are different. The RS shale at the lower part of the LMX shale has a better OM quality and a greater TOCo, which result in the greater effective organic carbon (TOCe), gas production potential, and retained gas content. It is followed by the RM, LS, and LM shales. In contrast, the LA shale lacks material base for shale gas enrichment. Combined with the available data from other deep blocks in the southern Sichuan Basin, the original OM attributes of RS and RM shales are always better than those of LM, LS, and LA shales. For deep and ultra-deep Longmaxi shale gas exploration, the RS shale should be the first choice, and then the RM shale.

Numerical investigation on combustion regulation for a stoichiometric heavy-duty natural gas engine with hydrogen addition considering knock limitation

Aiming to further improve the thermal efficiency and reduce NOx emissions in the stoichiometric hydrogen-enriched natural gas (NG) engine, a detailed 3-D simulation model of stoichiometric operation heavy-duty NG engine is built based on the actual boundary conditions from high load bench test. The superimposed methods for knock regulation, combustion and emission control, including Miller valve timing, hydrogen volume fraction and EGR rate were proposed and investigated comprehensively. It reveals that the typically bimodal characteristic of heat release rate (HRR) curve is caused by knock, which seriously restricts the performance improvement of stoichiometric NG engine under high load condition. To predict and control the occurrence of the second peak of HHR accurately, a new parameter BI is defined. Moreover, the Miller timing with 20°CA of the intake valve late closing shows better combustion performance within the knock limit, accompanied by a slight increase in NOx emissions. Additionally, the 5% hydrogen blend, coupled with the Miller cycle, can further enhance the indicated thermal efficiency (ITE) of the NG engine due to the stronger effects on acceleration of laminar flame propagation velocity than the promotion of end-gas auto-ignition. Besides, the great potential of EGR rate for balancing NOx and ITE is also confirmed in the heavy-duty hydrogen-enriched NG engine adopting Miller cycle. Compared to the original indexes, combing with the regulation strategies of intake valve late closing (20°CA), hydrogen addition (5%) and EGR (17%) are proved to increase the indicated thermal efficiency by 1.89% and reduce NOx emissions by 11.47% within the knock limit.