Environmental Management Research Research Articles

Risk assessment of land subsidence based on GIS in the Yongqiao area, Suzhou City, China.

This study focuses on the Yongqiao District in Suzhou City, Anhui Province, China, aiming to analyze the current situation of ground settlement and its influencing factors in the area. The selected risk indices include settlement rate, cumulative settlement amount, groundwater level drop funnel, thickness of loose sediment layer, thickness of soft soil layer, and the number of groundwater extraction layers. Additionally, vulnerability indices such as population density, building density, road traffic, and functional zoning are considered. An evaluation index system for assessing land Subsidence risk was established. The risk evaluation of land Subsidence was conducted using the Hierarchical analysis-composite index method and ArcGIS spatial analysis, The evaluation results show that the area of higher risk area is about 2.82 km2, accounting for 0.96% of the total area, mainly distributed in the area of Jiuli village, Sanba Street. The middle risk area is distributed around the higher area, with an area of about 9.18 km2, accounting for 3.13% of the total area. The lower risk areas were distributed in most of the study area, covering an area of 222.24 km2, accounting for 75.82% of the total area. The low risk assessment area is mainly distributed in Bianhe Street and part of Zhuxianzhuang Town, with an area of about 58.88 km2, accounting for 20.09% of the total area. The findings of this study are not only crucial for informing local policies and practices related to land use planning, infrastructure development, and emergency response but also enhance our understanding of the complexities of land Subsidence processes and their interactions with human activities, informing future research and practice in environmental risk assessment and management.

Ethnoecological perspectives on environmental stewardship: Tenets and basis of reciprocity in Gitxsan and nłeʔkepmx (Nlaka'pamux) Territories

Abstract Local and Indigenous Peoples steward and protect a significant proportion of biologically diverse ecosystems globally. This fact is increasingly acknowledged by researchers and international organizations, offering both opportunities and challenges at the intersection of Indigenous and western knowledge production in the context of environmental management research and policy. Drawing on half a century of ethnoecological research and personal experiences in Gitxsan and nłeʔkepmx Territories in the Pacific Northwest of North America, this research considers the role of reciprocity as an inherent philosophy and tenet for successful environmental stewardship. Reciprocity is a legal responsibility and moral perspective that foregrounds many Indigenous worldviews. Such cultural drivers and obligations towards lands and biota appear to be unknown, marginalized or instrumentalized in mainstream and western science and policy. We conclude that fundamental elements of reciprocity may not be adequately blended or braided into western environmental management frameworks. As such, alternatives to blending include acknowledging sole proprietary and self‐determining rights for Indigenous Peoples to govern and steward lands outside of western infrastructures and value systems. This study raises critical questions about the feasibility of reconciling reciprocity with western environmental management practices and regulations. It explores the implications for Indigenous rights and sovereignty, and climate change mitigation. By addressing these complex issues, we contribute to ongoing discourse on the integration of Indigenous and western knowledge in environmental stewardship research, and the ethical, historical and cultural challenges that come with it. Read the free Plain Language Summary for this article on the Journal blog.

Experimental study for visualizing CO2-dissolved water plume migration under hydraulic gradient conditions and implication for field monitoring data

Investigating the possible direction of a CO2-dissolved water plume migration near the potential CO2 leakage area is a significant task because it helps estimate the spatial and temporal monitoring scale to detect the signal of released CO2 from the storage. Accordingly, the Korea CO2 Storage Environmental Management (K-COSEM) research center tried to develop an intensive monitoring system and applied it to the artificial CO2 release test in the actual field. Monitoring data from the field tests depicted the horizontal movement of the CO2-dissolved water plume along the direction of the groundwater flow. However, it remains unclear how the CO2-dissolved water plume migrates vertically and how gas accumulation occurs near the capillary zone. The present study simulated the CO2 release test with a visual expression method utilizing a Hele-Shaw cell with hydraulic gradient conditions (i = 0, 0.1, and 0.01) and tried to estimate the significant influences on a diffusive-advective transport of the dissolved gas plume with the shallow aquifer condition. The visualization experiment results were intuitively verified to determine whether the theoretical principles of action related to plume flow applied in this context. The results suggest that a CO2-dissolved water plume is distributed by hydraulic gradients and density-driven CO2 convective flow. The plume shape, center, and area were analyzed using an image analyzer program; the results demonstrated that the plume characteristic evolved depending on the significant effects on the plume. When the plume was mainly affected by the hydraulic gradient, it rapidly moved from the injection point to the last boundary; in contrast, when it was influenced primarily by density-driven CO2 convective flow, it flowed diagonally downward in the shape of varied branches. The numerical model calculated the migration of the CO2-dissolved water plume affected by both factors. The laboratory experiment and numerical simulation results suggest that the migration of a CO2-dissolved water plume may be affected by the hydraulic gradient and density-driven CO2 convective transport. As such, these factors should be considered when designing and analyzing CO2 monitoring signals to detect CO2 leaks from shallow aquifer systems.

Comprehensive environmental management research for indoor sports and fitness facilities in community sports center

Formaldehyde, as one of the main indoor air pollutants, poses a significant threat to human health. Therefore, to effectively reduce indoor formaldehyde pollution, we prepare a novel silver carbonate (Ag2CO3)/amorphous silver silicates (a-AgSiO)/g-C3N4 nanosheets (CNNS) composite catalyst using in-situ precipitation and ion exchange methods. The Ag2CO3/a-AgSiO/CNNS composite was characterized by various methods, including XRD, FT-IR, and XPS. Compared to the a-AgSiO/CNNS composite, the formaldehyde degradation efficiency of the Ag2CO3/a-AgSiO/CNNS composite is significantly enhanced, reaching up to 81.9% under the same conditions. Cycling stability tests also demonstrated the excellent chemical stability of the Ag2CO3/a-AgSiO/CNNS composite, with a formaldehyde degradation efficiency of 72.6% after five cycles. By investigating the mechanism of Ag2CO3/a-AgSiO/CNNS composite, we found that the formation of double Z-type heterogeneous structure in the Ag2CO3/a-AgSiO/CNNS composite enhanced the separation efficiency of photoinduced charge carriers and improved the photocatalytic activity. In conclusion, the prepared Ag2CO3/a-AgSiO/CNNS composite catalyst with excellent photocatalytic performance can be used for the efficient degradation of indoor formaldehyde.

Analysing and Anticipating Conflict Using a Values-Centred Online Survey

The authors present an approach to conceptualising and predicting environmental conflicts in which conflicts are analysed as a continuum of disagreement over values and options. They also operationalise this approach using an online values-centred survey tool, the ‘public-to-public decision support system’ (P2P-DSS). The authors put values and conflict in environmental management into perspective. Next, they review how values are defined in scholarship and operationalised for decision support. The relevance of values research to con-flict management is presented. With reference to a real-world aggregate-mining conflict, the authors demonstrate how P2P-DSS can be used to collect data and categorise conflicts to enhance environmental management decision-making. The authors argue that P2P-DSS has potential to support values-sensitive thinking for environmental conflict management. They then set out research priorities to investigate the theoretical and practical implications of this approach. This work contributes to advancing values research in environmental conflict management and expanding values-based decision-making.

Distinguishing between research and monitoring programs in environmental science and management

The terms “research” and “monitoring” are commonly used interchangeably to describe the data-gathering, information-generating, and knowledge-translating activities in environmental science and management. While research and monitoring share many attributes, such as the tools used, they may also differ in important ways, including the audience and their stability. In any environmental program, any potential differences between research and monitoring may be inconsequential, but distinguishing between these two activities, especially when both words are used casually, may be necessary to ensure the alignment between the tools and approaches and the expectations and goals of the program. Additionally, the importance of distinguishing between research and monitoring becomes greater when many participants from varying backgrounds with differing expectations are involved in the design, execution, and governance of the program. In this essay, we highlight differences between environmental research and monitoring, provide potential criteria to define them, and discuss how their activities interact and overlap. In our view, environmental monitoring programs are typically standardized and designed to address stakeholder concerns, to ensure activities comply with regulatory statutes or other known objectives. In contrast, environmental research may be esoteric, driven by a specific line of inquiry, and may lack a defined endpoint. Although potential difficulties with categorizing some programs or portions of combined programs will likely always remain, explicitly identifying the attributes of a program is necessary to achieve its objectives.

RESEARCH IN ECO-TOURISM IN KAZAKHSTAN AS A SUCCESSFUL MECHANISM IN THE DEVELOPMENT OF ENVIRONMENTAL TOURISM MANAGEMENT

The purpose of this study is to determine the current level of ecotourism research in tourism environmental management of Kazakhstan and to perform a comparison assessment in order to gain a better understanding through critical analysis and the identification of gaps for future studies.Methodology. Analysis, comparison, and literature review have been used as the methods of this work.The originality / value of the study is an accurate analysis of the present situation of ecotourism research in Kazakhstan and Bhutan. The Bhutanese example of ecotourism research could contribute for the further development of tourism environmental management in Kazakhstan. Findings. The authors found a few main problems of ecotourism research, including having lack of comprehensive data and information and problems with regulatory legal acts and documents in Kazakhstan. Therefore, right ecotourism study can facilitate to the development of the tourism environmental management in Kazakhstan.Through analyzing the Bhutanese practice of ecotourism research, the authors found a gap in Kazakhstan tourism environmental management where further research should be focused. Consequently, the authors gave a few recommendations on the further development of ecotourism research in Kazakhstan, as working with closely with foreign experienced researchers, improving the protected areas websites, establishing a trust fund with other countries, improving government documents on tourism environmental management, publishing more reports in English, and providing more grants and scholarships.

Toward a new understanding of environmental and financial performance through corporate social responsibility, green innovation, and sustainable development

The study’s primary objective is to advance the environmental management research field by examining the relationship between corporate social responsibility (CSR), environmental and financial performance while considering the mediating effect of sustainable development and green innovation. In addition, the study also analyzes the moderating effect of green innovation actions and green innovation strategies. Employees in the manufacturing sector in Pakistan completed a self-administered survey. Data gathered from 497 employees was analyzed using the structural analysis. The study results show that corporate social responsibility to the environment (CSREM), corporate social responsibility to employees (CSREM), to the community (CSRCO), and to the consumers (CSRCO) positively influences environmental performance (EVP) and financial performance (FP). Environmental sustainable development (ESD) and green innovation (GI) mediate the relationship between CSR, environmental, and firm financial performance. Green innovation strategies (GINS) and green innovation actions (GINAs) moderate the relationship between a firm’s environmental and financial aspects. The study deepens the understanding of CSR through an integrated model of mediator and moderator variables. It attempts to boost the firms’ performance (i.e., environmental, and financial) by applying the concept of green innovation and sustainable development. This study brings significant results for manufacturing firms, managers, entrepreneurs, policymakers, practitioners, employees, and other stakeholders. The study’s outcomes make the stakeholders adopt CSR consideration to achieve ecological and financial harmony in developing economies.

AI explainability framework for environmental management research

Deep learning networks powered by AI are essential predictive tools relying on image data availability and processing hardware advancements. However, little attention has been paid to explainable AI (XAI) in application fields, including environmental management. This study develops an explainability framework with a triadic structure to focus on input, AI model and output. The framework provides three main contributions. (1) A context-based augmentation of input data to maximize generalizability and minimize overfitting. (2) A direct monitoring of AI model layers and parameters to use leaner (lighter) networks suitable for edge device deployment, (3) An output explanation procedure focusing on interpretability and robustness of predictive decisions by AI networks. These contributions significantly advance state of the art in XAI for environmental management research, offering implications for improved understanding and utilization of AI networks in this field.

Penegakan Hukum Administrrasi Pengelolaan Lingkungan Hidup di Lokasi Pertambangan

The surveillance provided by the energy service and mineral resources inspector of the southeast province of sulawesi in 2019 revealed mining operations that had not taken a good look at contamination prevention and environmental damage. Problem 1) how does the management of the environment at the mine location in northern stick 2) how does improving the management of the environment at mine location in northern stick. The purpose of research 1) to analyze the management of the environment at the mine location in northern konawe 2) to analyze the improved management of the environment at the mine location in northern konawe. The type of empirical legal research for primary data in interviews and observations supported by secondary data. The results of environmental management research have been carried out by authorities from the elements inspector of the ward service mine through the development and control of the operation of the mining operations. Through the phasing procedures, fines and penalties of the mining stops. The control and development of the 2021-2022 found two mining companies in violation of the code of mining law.

Do corporate anti-bribery and corruption commitments enhance environmental management performance? The moderating role of corporate social responsibility accountability and executive compensation governance

This study aims to examine the potential impact (substantive or symbolic) of firms' anti-bribery and corruption commitments (ABCC) on environmental management performance (ENVS). We also seek to explore whether this link is contingent on corporate social responsibility (CSR) accountability and executive compensation governance. To achieve these aims, we use a sample of 2151 firm-year observations representing 214 FTSE 350 non-financial companies from 2002 to 2016. Our findings support a positive association between firms’ ABCC and ENVS. In addition, our evidence shows that CSR accountability and executive compensation governance are significant substitutes for ABCC to engender enhanced ENVS. Our study highlights practical implications for organisations, regulators and policymakers, and suggests several avenues for future environmental management research. Overall, our findings are unsensitive to alternative measures of ENVS, different types of multivariate regression methods, namely ordinary least squares (OLS) and two-step generalized method of moments (GMM) regressions, and controlling for industry environmental risk and the implementation of the UK Bribery Act 2010.

Green resource orchestration: A critical appraisal of the use of resource orchestration in environmental management research, and a research agenda for future study

AbstractResource orchestration (RO) is a strategic management framework that details various processes by which how firms structure, bundle, and leverage resources. This study reviews how RO has been considered in environmental management research. The review highlights some limitations on how RO has been used in studies on environmental management, and it also illustrates a lack of knowledge accumulation in the field. To realize the full potential of RO, the concept of green RO is developed. Green RO (GRO) is defined as a firm's capability to coordinate and manage the structuring of resources and the bundling and leveraging of capabilities to create economic value for the company while simultaneously creating environmental benefits. Three main research areas for GRO are described: GRO as an organizational or managerial meta‐capability, management of specific GRO processes, and the synchronization of several GRO processes.

Bibliometric Analysis of Environmental, Social, and Governance Management Research from 2002 to 2021

Extreme weather events caused by climate change have increased people’s focus on sustainability. Environmental, social, and governance management (ESGM) has become crucial for corporate operations and development; ESGM has attracted the attention of the academic communities, and the number of related studies has continued to increase. However, this topic is multidisciplinary and diverse; therefore, this study used the Web of Science Core Collection Database to conduct a bibliometric analysis of ESGM-related articles published from 2002 to 2021. Bibliometrix (R language), VOSviewer, and CiteSpace were used to identify and analyze research trends related to the number of studies, research fields, authors, national institutions, and keywords. The importance of management and governance was identified through keyword analysis; important keywords identified were financial performance, adaptive governance, property rights, sustainable development goals, and corporate governance.

Functional responses of key marine bacteria to environmental change - toward genetic counselling for coastal waters.

Coastal ecosystems deteriorate globally due to human-induced stress factors, like nutrient loading and pollution. Bacteria are critical to marine ecosystems, e.g., by regulating nutrient cycles, synthesizing vitamins, or degrading pollutants, thereby providing essential ecosystem services ultimately affecting economic activities. Yet, until now bacteria are overlooked both as mediators and indicators of ecosystem health, mainly due to methodological limitations in assessing bacterial ecosystem functions. However, these limitations are largely overcome by the advances in molecular biology and bioinformatics methods for characterizing the genetics that underlie functional traits of key bacterial populations - "key" in providing important ecosystem services, being abundant, or by possessing high metabolic rates. It is therefore timely to analyze and define the functional responses of bacteria to human-induced effects on coastal ecosystem health. We posit that categorizing the responses of key marine bacterial populations to changes in environmental conditions through modern microbial oceanography methods will allow establishing the nascent field of genetic counselling for our coastal waters. This requires systematic field studies of linkages between functional traits of key bacterial populations and their ecosystem functions in coastal seas, complemented with systematic experimental analyses of the responses to different stressors. Research and training in environmental management along with dissemination of results and dialogue with societal actors are equally important to ensure the role of bacteria is understood as fundamentally important for coastal ecosystems. Using the responses of microorganisms as a tool to develop genetic counselling for coastal ecosystems can ultimately allow for integrating bacteria as indicators of environmental change.

Are small and medium enterprises beneficial from the adoption of green market orientation under the intensity of market competition? A strategic alignment perspective

Abstract There is limited knowledge regarding whether market competition (MC) influences the adoption of green market orientation (GMO) by small and medium enterprises (SMEs). Moreover, there is no clear understanding of whether the strategic alignment between differentiation strategy (DS) and the adoption of GMO and MC accounts for these enterprises’ financial performance (FP). This study aims to draw on contingency theory and the natural resource-based view to shed light on these questions by proposing a research model, which demonstrates the relationship between MC and GMO and the mediating effects of DS on the relationship between MC, GMO, respectively, and FP. Data were collected from 172 SMEs that are currently operating in Vietnam. The partial least square structural equation modelling technique was executed to examine the research model. The results reveal that the intensity of MC influences SMEs to adopt GMO. Furthermore, it was also shown that DS fully mediates the relationship between MC, GMO, and FP. This study provides four significant contributions to environmental management research and contingency theory. In addition, this study provides crucial practical implications for SMEs operating in Vietnam.

Water-Quality Assessment and Pollution-Risk Early-Warning System Based on Web Crawler Technology and LSTM.

The openly released and measured data from automatic hydrological and water quality stations in China provide strong data support for water environmental protection management and scientific research. However, current public data on hydrology and water quality only provide real-time data through data tables in a shared page. To excavate the supporting effect of these data on water environmental protection, this paper designs a water-quality-prediction and pollution-risk early-warning system. In this system, crawler technology was used for data collection from public real-time data. Additionally, a modified long short-term memory (LSTM) was adopted to predict the water quality and provide an early warning for pollution risks. According to geographic information technology, this system can show the process of spatial and temporal variations of hydrology and water quality in China. At the same time, the current and future water quality of important monitoring sites can be quickly evaluated and predicted, together with the pollution-risk early warning. The data collected and the water-quality-prediction technique in the system can be shared and used for supporting hydrology and in water quality research and management.

Application of “Theory of Change” in trans-disciplinary research at Lap Giai Domestic Wood Company, Ben Cat District, Binh Duong Province

This article is the results of the project "Assessment of health and safety risks for wood industry workers researched at Lap Giai Company, Ben Cat district, Binh Duong province". Theory of change (ToC) is an intervention strategy to reduce worker health risk and safety that was initially established by the research team before being deployed at Lap Giai Company. Preparation ToC helps promote and cooperate in the co-production of knowledge between the academic and management group. The paper is a summary of 10 steps of the ToC method, in which, planning, analyzing change needs, projecting impacts, mapping intermediate results, determining project outputs, identifying assumptions, creating diagrams and explaining the ToC are important steps. The experiences drawn from the theory of change in transdisciplinary study are (1) can be applied to digital transformation research and environmental management research in enterprises. (2) Role leadership is decisive in developing transdisciplinary topics in enterprises. (3) Both internal and external environments must be considered to design the most beneficial change interventions.

Stainless steel catalyst for air pollution control: structure, properties, and activity.

With the awakening of environmental awareness, the importance of air quality to human health and the proper functioning of social mechanisms is becoming increasingly prominent. The low cost and high efficiency of catalytic technique makes it a natural choice for achieving deep air purification. Stainless steel alloys have demonstrated their full potential for application in a variety of catalytic fields. The diversity of 3D networks or fibrous structures increases the turbulence within the heterogeneous catalysis, balance the temperature distribution in the reaction bed and, in combination with a highly thermally conductive skeleton, avoid agglomeration and deactivation of the active components; corrosion resistance and thermal stability are adapted to highly endothermic/exothermic or corrosive reaction environments; oxide layers formed by bulk transition metals activated by thermal treatment or etching can significantly alter the physico-chemical properties between the substrate and active species, further improving the stability of stainless steel catalysts; suitable electronic conductivity can be applied to the electrothermal catalysis, which is expected to provide guidance for the reduction of intermittent emission exhausts and the storage of renewable energy. The current applications of stainless steel as catalyst or support in the air purification have covered soot particle capture and combustion, catalytic oxidation of VOCs, SCR, and air sterilization. This paper summarizes several preparation methods and presents the relationships between the preparation process and the activity, and reviews its application and the current status of research in atmospheric environmental management, proposing the advantages and challenges of the stainless steel-based catalysts.

Butterfly Identification App (BIA): A mobile application for identification and monitoring of butterflies in the state of Karnataka

Butterflies attract the attention of everyone, but it is difficult to identify and know their names instantly. Even for the students and researchers, identifying them in the field itself necessitates capturing and referring field guides. A novel mobile application known as Butterfly Identification App (BIA) has been developed by Environmental Management and Policy Research Institute EMPRI, Bengaluru, India to identify butterflies in the field. It is a colour-based identification application, which can be used by anyone having an android mobile phone. It is not necessary to capture the butterflies but photos taken can be compared with the photos in the colour based groups in the BIA database. The identification of all butterflies reported from Karnataka is possible through the BIA. The usage of this by proficient taxonomists, students and environmentalists can contribute to the monitoring and conservation of butterfly species in their localities. Pilot studies conducted in six green spaces in Bengaluru (12.9716° N, 77.5946° E) with GPS locations (Lalbhag: 12.9487,77.5887; Cubbon Park: 12.9798,77.5968; Doresanipalya: 12.8971,77.5905; IISc: 13.0173,77.5712; GKVK: 13.0808,77.5677; Bannerghatta: 12.785,77.5745) using the BIA is presented in the paper

Preface

Abstract The 2022 International Conference on Electrical, Power and Grid Systems (ICEPGS 2022) was planned to be held on February 25-27, 2022 in Guangzhou, China. Currently, the entire world is struggling against the virulent pandemic COVID-19. Unfortunately, each of us is affected, either overtly or covertly. Our conference, 2022 International Conference on Electrical, Power and Grid Systems (ICEPGS 2022) was not an exception. Nowadays, mass gatherings are not permitted by the government. It is uncertain when the COVID-19 would end, so it remains unclear for postponement time, while many scholars and researchers wanted to attend this long-waited conference and have academic exchanges with their peers. Therefore, in order to actively respond the call of the government, and meet author’s request, the ICEPGS 2022, which was planned to be held in Guangzhou, China from February 25-27, 2022, was changed to be held online through Zoom software. This approach not only reduces people gathering, but also meets their communication needs. ICEPGS 2022 is to bring together innovative academics and industrial experts in the field of energy engineering, electrical engineering, Power Engineering and Grid Systems to a common forum. The primary goal of the conference is to promote research and developmental activities in energy engineering, electrical engineering and materials application and another goal is to promote scientific information interchange between researchers, developers, engineers, students, and practitioners working all around the world. During the conference, the conference model was divided into three sessions, including oral presentations, keynote speeches, and online Q&A discussion. In the first part, some scholars, whose submissions were selected as the excellent papers, were given about 5-10 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches. There were over 90 participants attended the meeting. In the second part, we invited four professors as our keynote speakers. The first keynote speaker, Prof. Chong Kok Keong, Universiti Tunku Abdul Rahman, Malaysia. His research interest including concentrating solar power, concentrator photovoltaic system, photovoltaic, daylighting and solar thermal system. And then we had Prof. Mohammad Dalour Hossen Beg, Universiti Malaysia, Pahang, Malaysia. His major research area is Polymer and Composites. Likewise, his other research area is the production and characterization of nanoparticles, and production of nanocomposites. Prof. Qinghua Liu, University of Science and Technology of China. His current research interests mainly focus on the construction of advanced energy catalytic materials and the in-situ synchrotron radiation characterizations of advanced energy conversion systems. Lastly, we invited A. Prof. Muhammad Jawad Sajid, from Xuzhou University of Technology. He has a strong interest in environmental management research. In particular, he has vast experience with carbon emissions, carbon footprints, and carbon policy. Their insightful speeches had triggered heated discussion in the third session of the conference. Every participant praised this conference for disseminating useful and insightful knowledge. The proceedings are a compilation of the accepted papers and represent an interesting outcome of the conference. Topics include but are not limited to the following areas: Advanced Power Semiconductors, Communication Systems, Electrical Materials and Process, Mechatronics and Robotics, Power System Stability and more related topics. All the papers have been through rigorous review and process to meet the requirements of international publication standard. We would like to acknowledge all of those who supported ICEPGS 2022. The help and contribution of each individual and institution was instrumental in the success of the conference. In particular, we would like to thank the organizing committee for its valuable inputs in shaping the conference program and reviewing the submitted papers. The Committee of ICEPGS 2022 List of Committee member, Conference Chairs, Conference General Chair, Publication Chairs, Program Committee, International Technical Committee, Organize Committee are available in this Pdf.