
\subsection{6.5 Lifecycle Cost Planning and TVM Analysis}

\begin{center}
\textbf{Cash Flow Diagram for Control-Based Station (5-Year Lifecycle)}
\end{center}

\begin{tikzpicture}[>=Stealth, scale=1, every node/.style={scale=1}]
  % Draw timeline
  \draw[->] (0,0) -- (6.5,0) node[right] {Time (Years)};
  \foreach \x in {0,1,2,3,4,5} {
    \draw (\x,0.1) -- (\x,-0.1) node[below] {\x};
  }

  % Year 0 - Initial Investment
  \draw[->, thick] (0,0) -- (0,-3) node[below] {- \$1000};

  % Years 1–4 - Annual Operating Cost
  \foreach \x in {1,2,3,4} {
    \draw[->, thick] (\x,0) -- (\x,-1) node[below] at (\x,-1.2) {- \$100};
  }

  % Year 5 - Annual Cost + Salvage
  \draw[->, thick] (5,0) -- (5,-1) node[below left] {- \$100};
  \draw[->, thick, green!60!black] (5,0) -- (5,2) node[above] {+ \$200};

  % Labels
  \node at (3,-3.8) {Cash Outflows = CAPEX \& OPEX};
  \node at (5.8,2.5) {Salvage Value};
\end{tikzpicture}
\section{System Engineering Management Plan (SEMP)}

This section outlines the methodology, tools, and resources used to develop, analyze, and manage the system in accordance with systems engineering best practices.

\subsection{Lifecycle Approach}
This project follows a V-Model-inspired process, progressing from stakeholder requirements through system design, component selection, and preparation for verification.

\subsection{Engineering Activities}
\begin{itemize}
    \item \textbf{Modeling Method}: Descriptive MBSE approach using function hierarchy, FFBDs, N-diagrams, and allocation tables.
    \item \textbf{System Design}: Evaluation of alternatives via AHP, selection of components, function-to-component mapping.
    \item \textbf{Verification Prep}: Requirement traceability ensures every component and function aligns with stakeholder needs.
\end{itemize}

\subsection{Organizational Roles}
\begin{itemize}
    \item \textbf{System Engineer}: Leads system analysis, design, and validation (single-author thesis project).
    \item \textbf{User / Stakeholder}: Farmers or homesteaders maintaining and interacting with the system.
    \item \textbf{Open Source Community}: Supports software packages, updates, and ecosystem tools.
\end{itemize}

\subsection{Key Milestones}
\begin{table}[H]
\centering
\caption{SEMP Development Milestones}
\begin{tabular}{|l|l|}
\hline
\textbf{Phase} & \textbf{Deliverable} \\
\hline
Requirements Analysis & Functional and Non-Functional Requirements \\
Conceptual Design     & FFBDs, N-diagrams, Function Allocation Tables \\
Component Architecture & Component Hierarchy, Flow Diagrams, Cost Model \\
Verification Planning & Requirement Traceability Matrix \\
Deployment Preparation & Configuration Table, Maintenance Strategy \\
\hline
\end{tabular}
\end{table}

\subsection{Cost Model}

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.

\begin{table}[H]
\centering
\caption{Estimated First-Year and Annual Operating Costs}
\begin{tabular}{|l|l|l|}
\hline
\textbf{Category} & \textbf{One-Time Cost (USD)} & \textbf{Annual Cost (USD)} \\
\hline
Edge Device (Raspberry Pi 4 + Peripherals) & \$100 & -- \\
Sensors (Weather Station + Soil Probes)    & \$200 & -- \\
4G Modem + SIM Hardware                    & \$50  & -- \\
Solar Power Kit + Battery Storage          & \$150 & -- \\
Weatherproof Enclosure                     & \$30  & -- \\
Data Connectivity (4G SIM, low-data)       & --    & \$6--\$12 \\
Preventive Maintenance Buffer              & --    & \$50 \\
Cloud/Remote Logging (Optional)            & --    & \$60 \\
\hline
\textbf{Total Estimate}                    & \textbf{\$530} & \textbf{\$116--\$122} \\
\hline
\end{tabular}
\end{table}

\noindent
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.

