Emerging Trends and Future IoTIntroduction and ContextThe Internet of Things (IoT) has evolved from a collection of connected sensors into a distributed socio-technical system involving embedded computing, communication networks, cloud platforms, artificial intelligence (AI), digital twins, robotics, industrial control, and human institutions. Early IoT implementations primarily focused on remote monitoring and data collection. Contemporary systems increasingly support autonomous decision-making, collaborative intelligence, real-time control, and integration with critical infrastructure. The future of IoT is therefore not defined merely by connecting more devices. It is defined by improving the quality, timeliness, explainability, security, sustainability, and economic value of interactions among physical objects, computational services, organizations, and people. Postgraduate study requires analysis of both technological possibilities and the conditions under which these possibilities can be responsibly implemented. IoT systems are becoming more distributed. Data may be processed on a sensor, gateway, edge server, cloud platform, or across several of these locations. Communication is becoming more heterogeneous through 5G, 6G research, low-power wide-area networks, satellite links, industrial Ethernet, and emerging non-terrestrial networks. Intelligence is moving from centralized cloud services toward edge and federated architectures. At the same time, legal, ethical, and environmental constraints are becoming as important as technical performance. Learning ObjectivesAfter completing this chapter, learners should be able to: - Explain major emerging trends shaping the future of IoT.
- Compare cloud, edge, fog, and distributed IoT architectures.
- Analyze the roles of AI, federated learning, digital twins, 5G/6G, and blockchain-related technologies.
- Evaluate IoT systems using technical, economic, ethical, security, and sustainability criteria.
- Design a responsible future-IoT strategy for a realistic application domain.
- Identify research challenges and unresolved questions in IoT engineering.
1. From Connected Devices to Intelligent Cyber-Physical SystemsA conventional connected device reports measurements to an application. A future cyber-physical IoT system forms a feedback loop: it senses a physical process, interprets data, makes or supports a decision, acts through an actuator, and observes the resulting change. The key distinction is that the system participates in the process rather than simply describing it. A useful abstraction is: x(t+1) = f(x(t), u(t), w(t)) Here, x(t) is the physical state at time t, u(t) is the control input, w(t) represents disturbances or uncertainty, and f is the system dynamics. This model is applicable when the physical process can be represented in discrete time. It does not imply that all IoT systems are deterministic or that the exact state is observable. The sensing and decision process can be represented as: y(t) = h(x(t), v(t)) where y(t) is the observed measurement, h is the measurement function, and v(t) is measurement noise. In practice, sensor calibration, missing data, communication delay, and adversarial manipulation affect the reliability of y(t). This perspective leads to five characteristics of future IoT: - Context awareness: interpretation depends on location, time, user, environment, and operating conditions.
- Adaptivity: system behavior changes in response to data and changing objectives.
- Autonomy: routine decisions occur without continuous human intervention.
- Interoperability: devices and services operate across vendors and administrative domains.
- Accountability: decisions and actions can be traced, justified, audited, and contested.
2. Distributed Intelligence: Cloud, Edge, and Fog ComputingCloud computing offers elastic storage, large-scale analytics, centralized management, and access to advanced AI models. However, sending all raw IoT data to a distant cloud can produce excessive bandwidth use, latency, privacy exposure, and dependence on continuous connectivity. Edge computing places processing close to data sources, such as sensors, gateways, vehicles, factory controllers, or local servers. Fog computing is a broader distributed model in which processing, networking, storage, and management functions are placed across multiple intermediate nodes between devices and the cloud. The terms overlap in industry usage, but edge generally emphasizes proximity to the data source, whereas fog emphasizes a distributed hierarchy. A deployment decision should consider latency, bandwidth, privacy, resilience, computational capacity, and operating cost. A simple end-to-end response time model is: Ttotal = Tsense + Tqueue + Tuplink + Tprocess + Tdownlink + Tactuate Each term represents sensing, queueing, uplink transmission, processing, downlink transmission, and actuation time. The units must be consistent, normally milliseconds. This additive model is useful for a sequential request-response path; parallel processing, retransmissions, and pipelining require a more detailed model. For a cloud-only design, Tuplink and Tdownlink may dominate. Edge processing can reduce network terms, but it may increase local hardware cost and maintenance complexity. A practical architecture often uses a hierarchy: - device-level filtering for immediate safety responses;
- gateway-level aggregation and protocol translation;
- edge-level real-time analytics and local control;
- cloud-level historical analysis, fleet optimization, and model training.
Edge AI and Tiny Machine LearningEdge AI executes inference near the data source. Tiny machine learning, often called TinyML, applies compressed models to microcontrollers with limited memory and energy. Common techniques include quantization, pruning, knowledge distillation, and feature extraction. A model may be evaluated using accuracy, precision, recall, latency, memory footprint, energy per inference, and robustness to distribution shift. Accuracy alone is insufficient. For a safety-critical application, a small improvement in average accuracy may not compensate for a dangerous false-negative rate. A binary classifier can be described using: Precision = TP / (TP + FP) Recall = TP / (TP + FN) Here, TP, FP, and FN are true positives, false positives, and false negatives. These measures apply when the positive class has operational meaning. In a medical monitoring system, for example, recall may be prioritized when missing a dangerous event is more harmful than generating an additional alert. 3. Artificial Intelligence, Machine Learning, and Autonomous IoTAI is becoming an integral component of IoT rather than an optional analytics layer. Important applications include predictive maintenance, demand forecasting, anomaly detection, computer vision, adaptive control, natural-language interaction, and optimization of energy and logistics networks. Predictive and Prescriptive IntelligencePredictive analytics estimates what is likely to happen. Prescriptive analytics recommends or executes an action. The distinction is important: a model predicting equipment failure does not itself determine whether to shut down a machine, schedule maintenance, or continue operation under observation. A robust IoT AI lifecycle includes: - problem definition and harm analysis;
- sensor selection and data-quality assessment;
- labeling and representative sampling;
- model development and validation;
- deployment with resource constraints;
- monitoring for drift and failure;
- human oversight and controlled retirement.
IoT data frequently exhibit non-stationarity. A model trained under one season, production recipe, demographic group, or network condition may perform poorly after conditions change. Therefore, model monitoring should include data drift, concept drift, calibration, and subgroup performance. Federated Learning and Privacy-Preserving IntelligenceFederated learning trains a shared model while retaining training data on local devices or sites. A simplified aggregation rule is: wt+1 = ∑k=1K (nk / n) wt+1(k) where wt+1 is the updated global model, wt+1(k) is the locally trained model from participant k, nk is that participant’s sample count, n = ∑k=1K nk, and K is the number of participants. This weighted averaging method assumes that model updates are compatible and that sample count is an acceptable weighting basis. It does not by itself guarantee privacy. Federated learning remains vulnerable to poisoning, inference attacks, unreliable participants, communication costs, and statistically heterogeneous data. Differential privacy, secure aggregation, trusted execution environments, and robust aggregation may be added, but each introduces computational, accuracy, or governance trade-offs. Generative AI may assist with IoT configuration, natural-language querying, code generation, synthetic data, and operator support. It should not be allowed to issue unrestricted control commands in safety-critical environments without authorization, validation, bounded action spaces, and fail-safe mechanisms. Generated explanations may be persuasive but inaccurate; explainability must therefore be tied to evidence, logs, and model behavior rather than fluent language alone. 4. Digital Twins and Real-Time System RepresentationA digital twin is a continuously updated digital representation of a physical entity, process, or system. A static 3D model is not necessarily a digital twin. A twin requires a meaningful relationship between the physical and digital systems, data synchronization, a defined purpose, and mechanisms for analysis or intervention. Digital twins may operate at several levels: - component twin: a motor, valve, battery, or sensor;
- asset twin: a machine, vehicle, or building;
- process twin: a manufacturing line or energy process;
- system-of-systems twin: a city, supply chain, or regional infrastructure network.
Core functions include state estimation, simulation, anomaly detection, scenario analysis, optimization, and predictive maintenance. A twin can be used to test a control policy virtually before applying it to the physical system, reducing operational risk. The value of a digital twin depends on model fidelity, data timeliness, uncertainty representation, interoperability, and lifecycle governance. Excessive model complexity can make a twin expensive to maintain. Conversely, an oversimplified model may support misleading decisions. A professionally designed twin should state its intended accuracy, update frequency, assumptions, and failure modes. 5. Connectivity Trends: 5G, 6G Research, Satellites, and Network ConvergenceModern IoT uses multiple connectivity classes rather than a single universal network. | Connectivity class | Typical strength | Typical limitation | Suitable applications |
|---|
| Short-range wireless | Low local power and cost | Limited range and interference sensitivity | Homes, buildings, wearables | | Low-power wide-area networking | Long battery life and broad coverage | Low data rate and message-size constraints | Agriculture, metering, environmental sensing | | Cellular IoT | Managed mobility and wide-area coverage | Subscription and infrastructure dependence | Fleets, logistics, cities | | Industrial wired networks | Predictable performance and reliability | Installation cost and limited mobility | Factories, substations | | Satellite and non-terrestrial networks | Remote-area coverage | Latency, power, and service cost | Maritime, disaster response, remote assets |
5G supports enhanced mobile broadband, massive machine-type communication, and ultra-reliable low-latency communication as important design goals. Actual performance depends on spectrum, deployment density, backhaul, device capability, traffic load, and service configuration. A claim that 5G automatically provides deterministic industrial control is therefore unjustified. Research toward 6G considers integrated sensing and communication, advanced positioning, AI-native networking, reconfigurable intelligent surfaces, terahertz communication, and tighter integration of terrestrial and non-terrestrial networks. These remain active research areas rather than universally available capabilities. Network slicing can create logically separated services over shared infrastructure. It can support different reliability, latency, and security policies, but isolation must be technically enforced and contractually governed. Software-defined networking and network function virtualization make network behavior more programmable, increasing flexibility but also expanding the attack surface. 6. Interoperability, Semantics, and the Internet of EverythingFuture IoT will contain heterogeneous devices, protocols, data models, organizational policies, and lifecycle practices. Interoperability is therefore more than the ability to exchange packets. It includes: - technical interoperability: systems can connect and communicate;
- syntactic interoperability: data structures and formats are understood;
- semantic interoperability: the meaning of data is preserved;
- organizational interoperability: business rules, responsibilities, and processes align.
Semantic models, digital ontologies, common identifiers, metadata, and standardized APIs reduce integration costs. Developers should distinguish an identifier from an attribute: an identifier refers to an entity, while an attribute describes a property that may change. Time, unit, accuracy, provenance, and quality status should accompany measurements. Data spaces and data-sharing ecosystems seek to enable controlled exchange across organizations while preserving sovereignty, access policies, and provenance. This is particularly important in smart cities, healthcare, manufacturing, and supply chains, where no single organization owns all necessary data. 7. Blockchain, Distributed Ledgers, and Decentralized IoTDistributed ledger technologies may support tamper-evident records, decentralized coordination, provenance, and automated agreements. Potential IoT uses include tracking custody in supply chains, registering device identities, recording maintenance events, and coordinating transactions among organizations that do not fully trust one another. A ledger is not automatically a solution to IoT security. It may introduce latency, storage overhead, governance disputes, key-management risks, and irreversible errors. Most sensor data should not be placed directly on a public ledger. A common pattern stores large data off-chain and records a cryptographic hash or reference on-chain. Blockchain is particularly inappropriate when a trusted, efficient central authority already exists and the problem does not require multi-party consensus. It also cannot prove that a sensor measurement was truthful at the moment it was recorded. Trust in the sensing process, calibration, identity, and physical security remains necessary. 8. Sustainable and Green IoTThe expansion of IoT creates environmental benefits and burdens. IoT may reduce energy use through intelligent control, optimize transport, detect water leakage, and improve maintenance. Conversely, billions of devices require materials, manufacturing energy, batteries, network infrastructure, data-center resources, and eventual disposal. Sustainable design should consider the full lifecycle: - material extraction and manufacturing;
- transportation and installation;
- operational energy and connectivity;
- maintenance and replacement;
- reuse, recycling, or safe disposal.
A simple operational energy estimate is: Etotal = Pactive tactive + Psleep tsleep where Etotal is energy in joules when power is measured in watts and time in seconds; Pactive and Psleep are active and sleep power; and tactive and tsleep are the corresponding durations. The formula assumes approximately constant power in each mode and excludes transmission losses unless they are included in the stated power values. For a sensor operating for one day, suppose active power is 60 mW for 10 seconds and sleep power is 0.2 mW for the remaining 86,390 seconds. Converting milliwatts to watts: Etotal = 0.060 × 10 + 0.0002 × 86,390 = 17.278 J The result is approximately 17.28 joules per day, excluding battery self-discharge and voltage-conversion losses. Although sleep power is small, its long duration makes it significant. Sustainable design therefore includes duty-cycle optimization, energy harvesting, repairability, software longevity, modular replacement, and responsible e-waste management. 9. Security, Safety, Privacy, and Trustworthy IoTFuture IoT systems increase the consequences of compromise because they can influence physical processes. Security objectives include confidentiality, integrity, availability, authenticity, accountability, and safety. These objectives may conflict. For example, aggressive security updates may temporarily reduce availability, while unrestricted availability may preserve a vulnerable service. A defense-in-depth strategy includes: - hardware roots of trust and secure boot;
- unique device identity and certificate-based authentication;
- least-privilege authorization;
- encrypted communication and protected data at rest;
- network segmentation and zero-trust principles;
- signed firmware and secure over-the-air updates;
- vulnerability disclosure and patch management;
- logging, monitoring, detection, and incident response;
- secure decommissioning and credential revocation.
Safety engineering must address hazards arising from both malfunction and malicious attack. A secure system can still be unsafe if its control logic is flawed. Safety cases, independent verification, fail-safe states, redundancy, graceful degradation, and human override are important in transportation, medical, energy, and industrial applications. Privacy is not limited to protecting names or passwords. Sensor data can infer occupancy, health, behavior, income, movement, or relationships. Privacy-by-design practices include data minimization, purpose limitation, retention controls, access transparency, local processing, anonymization where valid, and user or community participation. Regulatory requirements vary by jurisdiction and sector, but professional practice should address data protection, product security, critical infrastructure, radio spectrum, safety, accessibility, and environmental obligations. Compliance is a baseline, not a substitute for ethical judgment. 10. Human-Centered, Ethical, and Socially Responsible IoTIoT systems distribute decision power. A smart-city camera network, workplace monitoring system, or connected medical device can benefit users while also enabling surveillance, discrimination, coercion, or exclusion. Ethical evaluation should ask: - Who benefits and who bears the risks?
- Can affected people understand and contest decisions?
- Is consent meaningful, especially where participation is unavoidable?
- Are vulnerable groups disproportionately monitored or misclassified?
- What happens when connectivity or AI fails?
- Who is accountable for automated actions?
Important principles include autonomy, fairness, non-maleficence, beneficence, transparency, accessibility, and proportionality. Ethical review should occur during requirements analysis rather than after deployment. Public consultation, participatory design, impact assessments, and independent audits are practical governance mechanisms. 11. An Illustrative Case: Intelligent Water DistributionBackgroundConsider a fictional metropolitan water authority serving a rapidly growing city. The authority experiences leakage, intermittent pressure, manual meter reading, and delayed detection of pipe failures. ProblemThe authority proposes thousands of pressure, flow, acoustic, and quality sensors connected through a mixture of low-power wide-area and cellular networks. It also plans an AI system to identify leaks and a digital twin for network simulation. AnalysisA centralized cloud-only architecture would simplify fleet management but could delay emergency responses and expose detailed consumption patterns. Sensor readings are noisy and unevenly distributed; older neighborhoods may have fewer devices and poorer communication coverage. False alarms could waste maintenance resources, while missed leaks could damage infrastructure. Approach and SolutionThe proposed architecture uses local threshold detection at pumping stations, gateway aggregation in district control rooms, and cloud-based historical analytics. The digital twin represents pipes, valves, reservoirs, pumps, and pressure zones. AI models estimate the probability of a leak, but operators approve major interventions. Model performance is evaluated separately across districts to identify unequal error rates. Security controls include device identities, signed firmware, segmented operational networks, restricted remote access, and tested recovery procedures. Water-consumption data are retained only as long as operational and legal requirements justify. The authority publishes a plain-language explanation of data use and establishes a process for correcting inaccurate customer records. OutcomeIn this illustrative scenario, pilot deployment reduces time to detect major leaks and lowers unnecessary field inspections. However, the project also reveals that sensor maintenance, network coverage, model drift, and organizational coordination are more difficult than initial procurement. The digital twin is useful for scenario planning but is not treated as a perfect copy of the physical network. Learning Points- Technical architecture must reflect operational risk and response time.
- Edge processing can improve resilience but does not eliminate cloud value.
- AI requires continuous monitoring, not one-time validation.
- Digital twins are decision-support systems whose uncertainty must be explicit.
- Governance, privacy, and maintenance determine long-term value.
12. Future Research DirectionsSeveral research challenges remain open: - Scalable trust: how can billions of heterogeneous devices be authenticated, updated, and retired securely?
- Resource-constrained learning: how can models adapt on devices without excessive energy use?
- Continual and federated learning: how can systems learn from distributed, changing data while resisting poisoning?
- Semantic interoperability: how can independently developed systems agree on meaning, quality, and provenance?
- Verification of autonomous control: how can AI decisions be bounded and verified in uncertain physical environments?
- Resilient infrastructure: how should IoT operate during disasters, outages, cyberattacks, or degraded connectivity?
- Sustainable lifecycle design: how can environmental impact be quantified across devices, networks, and data centers?
- Human–AI collaboration: when should an operator trust, override, or retrain an autonomous system?
- Quantum and post-quantum readiness: how should long-lived devices transition to cryptographic methods resistant to future quantum threats?
Research should avoid evaluating systems only in laboratory conditions. Field trials, longitudinal studies, diverse populations, adversarial testing, lifecycle assessment, and reproducible datasets are necessary for credible conclusions. 13. Best Practices for Future-IoT DesignA professional future-IoT project should: - Define the physical problem and measurable value before selecting technology.
- Identify hazards, affected stakeholders, legal duties, and unacceptable outcomes.
- Use a reference architecture with explicit device, edge, network, platform, and application responsibilities.
- Select communication technologies according to latency, range, energy, reliability, and cost requirements.
- Treat identity, secure updates, logging, and decommissioning as lifecycle requirements.
- Use data minimization and privacy-preserving processing by default.
- Evaluate AI using operationally relevant metrics, uncertainty, drift, and subgroup performance.
- Design for interoperability through documented APIs, metadata, units, provenance, and standards.
- Test failure modes, degraded operation, recovery, and human override.
- Measure total lifecycle cost and environmental impact rather than initial purchase price alone.
- Establish ownership for data, models, devices, incidents, and decisions.
- Pilot incrementally, collect evidence, and scale only after technical and organizational validation.
Chapter SummaryFuture IoT is evolving toward intelligent, distributed, autonomous, and interconnected cyber-physical systems. Cloud, edge, and fog computing divide processing according to latency, bandwidth, privacy, resilience, and cost requirements. AI enables prediction, anomaly detection, optimization, and adaptive control, but model drift, bias, security, and explainability remain serious concerns. Federated learning can reduce centralized data movement but does not automatically guarantee privacy. Digital twins connect physical assets with continuously updated digital representations for monitoring, simulation, and optimization. 5G, satellite networks, software-defined networking, and research into 6G expand connectivity choices, while interoperability and semantic models determine whether heterogeneous systems can work together. Distributed ledgers may support provenance and coordination in selected multi-party settings but are not universal IoT solutions. Sustainable IoT requires lifecycle analysis covering materials, energy, maintenance, and disposal. Security, safety, privacy, ethics, and governance must be integrated from the beginning because IoT systems increasingly affect physical environments and human rights. The most successful future-IoT systems will combine technical innovation with measurable value, accountable automation, resilient architecture, inclusive design, and responsible lifecycle management. Key TermsCyber-physical system: A system in which computation, communication, sensing, and physical processes interact through feedback. Edge computing: Processing performed close to the source of IoT data. Fog computing: Distributed computing across devices, gateways, edge nodes, and cloud services. Edge AI: Artificial intelligence inference or learning performed near the data source. TinyML: Machine learning implemented on highly resource-constrained embedded devices. Federated learning: Collaborative model training in which data generally remain at local participants. Digital twin: A purposeful, data-connected digital representation of a physical entity or process. Network slicing: Logical separation of services with distinct performance or policy requirements over shared infrastructure. Semantic interoperability: Preservation of meaning when data move between independent systems. Distributed ledger: A replicated record maintained across multiple participants using an agreed consensus process. Lifecycle assessment: Evaluation of environmental impacts across a product or system’s lifecycle. Data drift: Change in the statistical properties of incoming data. Concept drift: Change in the relationship between inputs and the target or outcome. Zero trust: A security approach that continuously verifies access rather than automatically trusting network location. Secure boot: A mechanism that permits execution only of authenticated software during device startup. Digital provenance: Information describing the origin, history, transformation, and custody of data. Privacy by design: Incorporation of privacy protections into system architecture and development processes. Autonomous IoT: IoT capable of making or executing decisions with limited direct human intervention. Fail-safe state: A condition designed to minimize harm when a system detects failure or uncertainty. Review QuestionsShort Answer Questions- Distinguish edge computing from fog computing.
- Why is accuracy alone insufficient for evaluating an IoT AI model?
- What is the purpose of a digital twin?
- State two limitations of using blockchain in IoT.
- Why must IoT security include device decommissioning?
Long Answer Questions- Explain how cloud, edge, and fog computing can be combined in an industrial IoT architecture.
- Discuss the benefits and risks of federated learning for IoT analytics.
- Analyze the role of 5G, satellite connectivity, and future 6G research in heterogeneous IoT networks.
- Explain how sustainability should influence IoT design across the complete lifecycle.
- Discuss the relationship among cybersecurity, functional safety, privacy, and accountability in autonomous IoT.
Analytical / Application Questions- Design an IoT architecture for a remote agricultural system requiring low energy consumption, intermittent connectivity, and local irrigation control. Justify the placement of sensing, analytics, and actuation functions.
- An AI leak-detection model has high overall accuracy but misses most leaks in one low-income district. Analyze possible causes and propose technical and governance responses.
- A hospital plans to use connected wearable devices and an AI early-warning system. Develop a risk-based evaluation covering latency, reliability, privacy, model drift, human oversight, and failure recovery.
Multiple Choice Questions with AnswersQuestion 1Which characteristic most clearly distinguishes a cyber-physical IoT system from a basic monitoring system? A. It stores data in a database. B. It creates a feedback loop between computation and physical processes. C. It uses wireless communication exclusively. D. It eliminates the need for sensors. Correct Answer: B. It creates a feedback loop between computation and physical processes. Question 2Which processing location generally offers the lowest network-related response delay for a local control action? A. A distant public cloud region B. A remote data center on another continent C. An edge node near the physical process D. An archival storage system Correct Answer: C. An edge node near the physical process Question 3In the formula Precision = TP/(TP+FP), what does FP represent? A. False positives B. False predictions C. Failed processes D. Forward packets Correct Answer: A. False positives Question 4What is the principal objective of federated learning? A. To eliminate all model communication B. To train a shared model while retaining training data locally C. To store every sensor value on a blockchain D. To replace all edge devices with cloud servers Correct Answer: B. To train a shared model while retaining training data locally Question 5Which statement about a digital twin is most accurate? A. Any static 3D model is automatically a digital twin. B. A digital twin must be continuously connected to the public internet. C. A digital twin is a purposeful digital representation linked to a physical entity or process. D. A digital twin cannot support simulation. Correct Answer: C. A digital twin is a purposeful digital representation linked to a physical entity or process. Question 6Which issue is a limitation of blockchain for IoT? A. It always guarantees truthful sensor measurements. B. It can introduce consensus overhead and key-management risks. C. It cannot record any transaction history. D. It prevents all software updates. Correct Answer: B. It can introduce consensus overhead and key-management risks. Question 7Using Etotal = Pactive tactive + Psleep tsleep, what is the active energy when a device consumes 0.1 W for 20 s? A. 0.5 J B. 2 J C. 20 J D. 200 J Correct Answer: B. 2 J Question 8Which practice best represents privacy by design? A. Collecting all possible data indefinitely B. Using data minimization and purpose limitation from the design stage C. Publishing raw personal data for transparency D. Disabling access controls to improve usability Correct Answer: B. Using data minimization and purpose limitation from the design stage Question 9What does semantic interoperability preserve? A. Only the physical shape of a device B. The meaning of exchanged data C. Only the network cable type D. The battery chemistry of sensors Correct Answer: B. The meaning of exchanged data Question 10Why should future IoT systems be evaluated across their lifecycle? A. Initial purchase price is always the only relevant cost. B. Lifecycle evaluation includes manufacturing, operation, maintenance, and disposal impacts. C. Lifecycle evaluation removes the need for cybersecurity. D. It guarantees that all devices will have infinite battery life. Correct Answer: B. Lifecycle evaluation includes manufacturing, operation, maintenance, and disposal impacts.
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