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96 lines
4.2 KiB
96 lines
4.2 KiB
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\subsection{6.5 Lifecycle Cost Planning and TVM Analysis}
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\begin{center}
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\textbf{Cash Flow Diagram for Control-Based Station (5-Year Lifecycle)}
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\end{center}
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\begin{tikzpicture}[>=Stealth, scale=1, every node/.style={scale=1}]
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% Draw timeline
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\draw[->] (0,0) -- (6.5,0) node[right] {Time (Years)};
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\foreach \x in {0,1,2,3,4,5} {
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\draw (\x,0.1) -- (\x,-0.1) node[below] {\x};
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}
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% Year 0 - Initial Investment
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\draw[->, thick] (0,0) -- (0,-3) node[below] {- \$1000};
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% Years 1–4 - Annual Operating Cost
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\foreach \x in {1,2,3,4} {
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\draw[->, thick] (\x,0) -- (\x,-1) node[below] at (\x,-1.2) {- \$100};
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}
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% Year 5 - Annual Cost + Salvage
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\draw[->, thick] (5,0) -- (5,-1) node[below left] {- \$100};
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\draw[->, thick, green!60!black] (5,0) -- (5,2) node[above] {+ \$200};
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% Labels
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\node at (3,-3.8) {Cash Outflows = CAPEX \& OPEX};
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\node at (5.8,2.5) {Salvage Value};
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\end{tikzpicture}
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\section{System Engineering Management Plan (SEMP)}
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This section outlines the methodology, tools, and resources used to develop, analyze, and manage the system in accordance with systems engineering best practices.
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\subsection{Lifecycle Approach}
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This project follows a V-Model-inspired process, progressing from stakeholder requirements through system design, component selection, and preparation for verification.
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\subsection{Engineering Activities}
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\begin{itemize}
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\item \textbf{Modeling Method}: Descriptive MBSE approach using function hierarchy, FFBDs, N-diagrams, and allocation tables.
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\item \textbf{System Design}: Evaluation of alternatives via AHP, selection of components, function-to-component mapping.
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\item \textbf{Verification Prep}: Requirement traceability ensures every component and function aligns with stakeholder needs.
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\end{itemize}
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\subsection{Organizational Roles}
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\begin{itemize}
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\item \textbf{System Engineer}: Leads system analysis, design, and validation (single-author thesis project).
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\item \textbf{User / Stakeholder}: Farmers or homesteaders maintaining and interacting with the system.
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\item \textbf{Open Source Community}: Supports software packages, updates, and ecosystem tools.
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\end{itemize}
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\subsection{Key Milestones}
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\begin{table}[H]
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\centering
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\caption{SEMP Development Milestones}
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\begin{tabular}{|l|l|}
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\hline
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\textbf{Phase} & \textbf{Deliverable} \\
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\hline
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Requirements Analysis & Functional and Non-Functional Requirements \\
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Conceptual Design & FFBDs, N-diagrams, Function Allocation Tables \\
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Component Architecture & Component Hierarchy, Flow Diagrams, Cost Model \\
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Verification Planning & Requirement Traceability Matrix \\
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Deployment Preparation & Configuration Table, Maintenance Strategy \\
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\hline
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\end{tabular}
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\end{table}
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\subsection{Cost Model}
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The system is designed with strict cost constraints to ensure affordability for small-scale farmers and homesteaders. The goal is to maintain an annual operating cost below \$200 and a one-time hardware cost under \$1000, as specified in REQ-20 and REQ-26. The cost model incorporates hardware components, connectivity fees, and maintenance buffers.
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\begin{table}[H]
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\centering
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\caption{Estimated First-Year and Annual Operating Costs}
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\begin{tabular}{|l|l|l|}
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\hline
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\textbf{Category} & \textbf{One-Time Cost (USD)} & \textbf{Annual Cost (USD)} \\
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\hline
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Edge Device (Raspberry Pi 4 + Peripherals) & \$100 & -- \\
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Sensors (Weather Station + Soil Probes) & \$200 & -- \\
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4G Modem + SIM Hardware & \$50 & -- \\
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Solar Power Kit + Battery Storage & \$150 & -- \\
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Weatherproof Enclosure & \$30 & -- \\
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Data Connectivity (4G SIM, low-data) & -- & \$6--\$12 \\
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Preventive Maintenance Buffer & -- & \$50 \\
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Cloud/Remote Logging (Optional) & -- & \$60 \\
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\hline
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\textbf{Total Estimate} & \textbf{\$530} & \textbf{\$116--\$122} \\
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\hline
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\end{tabular}
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\end{table}
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\noindent
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The model assumes one centralized edge device performing both hub and compute functions. This reduces recurring data costs by minimizing transmission frequency and eliminates the need for cloud-hosted control services. The architecture supports expansion through additional sensors without significantly increasing operating costs.
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