Allow disposal at collection centers

CHANGELOG.md

@@ -11,6 +11,10 @@ All notable changes to this project will be documented in this file.
 [semver]: https://semver.org/spec/v2.0.0.html
 [pkjjl]: https://pkgdocs.julialang.org/v1/compatibility/#compat-pre-1.0
 
+## [Unreleased]
+
+- Allow product disposal at collection centers
+
 ## [0.5.1] -- 2021-07-23
 ## Added
 - Allow user to specify locations as unique identifiers, instead of latitude and longitude (e.g. `us-state:IL` or `2018-us-county:17043`)

Makefile

@@ -1,6 +1,6 @@
 JULIA := julia --project=.
 SRC_FILES := $(wildcard src/*.jl test/*.jl)
-VERSION := 0.5
+VERSION := dev
 
 all: docs test
 

src/instance/compress.jl

@@ -29,6 +29,8 @@ function _compress(instance::Instance)::Instance
         for (emission_name, emission_value) in p.transportation_emissions
             p.transportation_emissions[emission_name] = [mean(emission_value)]
         end
+        p.disposal_limit = [maximum(p.disposal_limit) * T]
+        p.disposal_cost = [mean(p.disposal_cost)]
     end
 
     # Compress collection centers
@@ -58,3 +60,42 @@ function _compress(instance::Instance)::Instance
 
     return compressed
 end
+
+function _slice(instance::Instance, T::UnitRange)::Instance
+    sliced = deepcopy(instance)
+    sliced.time = length(T)
+
+    for p in sliced.products
+        p.transportation_cost = p.transportation_cost[T]
+        p.transportation_energy = p.transportation_energy[T]
+        for (emission_name, emission_value) in p.transportation_emissions
+            p.transportation_emissions[emission_name] = emission_value[T]
+        end
+        p.disposal_limit = p.disposal_limit[T]
+        p.disposal_cost = p.disposal_cost[T]
+    end
+
+    for c in sliced.collection_centers
+        c.amount = c.amount[T]
+    end
+
+    for plant in sliced.plants
+        plant.energy = plant.energy[T]
+        for (emission_name, emission_value) in plant.emissions
+            plant.emissions[emission_name] = emission_value[T]
+        end
+        for s in plant.sizes
+            s.variable_operating_cost = s.variable_operating_cost[T]
+            s.opening_cost = s.opening_cost[T]
+            s.fixed_operating_cost = s.fixed_operating_cost[T]
+        end
+        for (prod_name, disp_limit) in plant.disposal_limit
+            plant.disposal_limit[prod_name] = disp_limit[T]
+        end
+        for (prod_name, disp_cost) in plant.disposal_cost
+            plant.disposal_cost[prod_name] = disp_cost[T]
+        end
+    end
+
+    return sliced
+end

src/model/build.jl

@@ -24,11 +24,15 @@ function create_vars!(model::JuMP.Model)
         (n, t) => @variable(
             model,
             lower_bound = 0,
-            upper_bound = n.location.disposal_limit[n.product][t]
+            upper_bound = n.location.disposal_limit[n.product][t],
         ) for n in values(graph.plant_shipping_nodes), t = 1:T
     )
     model[:collection_dispose] = Dict(
-        (n, t) => @variable(model, lower_bound = 0,) for
+        (n, t) => @variable(
+            model,
+            lower_bound = 0,
+            upper_bound = n.location.amount[t],
+        ) for
         n in values(graph.collection_shipping_nodes), t = 1:T
     )
     model[:store] = Dict(
@@ -90,7 +94,7 @@ function create_objective_function!(model::JuMP.Model)
     # Process node costs
     for n in values(graph.process_nodes), t = 1:T
 
-        # Transportation and variable operating costs
+        # Transportation costs
         for a in n.incoming_arcs
             c = n.location.input.transportation_cost[t] * a.values["distance"]
             add_to_expression!(obj, c, model[:flow][a, t])
@@ -137,7 +141,6 @@ function create_objective_function!(model::JuMP.Model)
 
     # Plant shipping node costs
     for n in values(graph.plant_shipping_nodes), t = 1:T
-
         # Disposal costs
         add_to_expression!(
             obj,
@@ -148,7 +151,6 @@ function create_objective_function!(model::JuMP.Model)
 
     # Collection shipping node costs
     for n in values(graph.collection_shipping_nodes), t = 1:T
-
         # Disposal costs
         add_to_expression!(
             obj,
@@ -170,7 +172,7 @@ function create_shipping_node_constraints!(model::JuMP.Model)
             model[:eq_balance][n, t] = @constraint(
                 model,
                 sum(model[:flow][a, t] for a in n.outgoing_arcs) ==
-                n.location.amount[t] + model[:collection_dispose][n, t]
+                n.location.amount[t] - model[:collection_dispose][n, t],
             )
         end
         for prod in model[:instance].products

src/model/solve.jl

@@ -29,29 +29,32 @@ function solve(
     instance::Instance;
     optimizer = nothing,
     output = nothing,
+    graph = nothing,
     marginal_costs = true,
     return_model = false,
 )
 
     milp_optimizer = lp_optimizer = optimizer
-    if optimizer == nothing
+    if optimizer === nothing
         milp_optimizer = _get_default_milp_optimizer()
         lp_optimizer = _get_default_lp_optimizer()
     end
 
+    if graph === nothing
         @info "Building graph..."
         graph = RELOG.build_graph(instance)
         _print_graph_stats(instance, graph)
+    end
 
     @info "Building optimization model..."
     model = RELOG.build_model(instance, graph, milp_optimizer)
 
     @info "Optimizing MILP..."
     JuMP.optimize!(model)
-
     if !has_values(model)
         error("No solution available")
     end
+    solution = get_solution(model, marginal_costs = false)
 
     if marginal_costs
         @info "Re-optimizing with integer variables fixed..."
@@ -65,12 +68,15 @@ function solve(
             end
         end
         JuMP.optimize!(model)
-    end
-
+        if has_values(model)
             @info "Extracting solution..."
-    solution = get_solution(model, marginal_costs = marginal_costs)
+            solution = get_solution(model, marginal_costs = true)
+        else
+            @warn "Error computing marginal costs. Ignoring."
+        end
+    end
 
-    if output != nothing
+    if output !== nothing
         write(solution, output)
     end
 
@@ -87,7 +93,7 @@ function solve(filename::AbstractString; heuristic = false, kwargs...)
     if heuristic && instance.time > 1
         @info "Solving single-period version..."
         compressed = _compress(instance)
-        csol = solve(compressed; output = nothing, marginal_costs = false, kwargs...)
+        csol, model = solve(compressed; output = nothing, marginal_costs = false, return_model = true, kwargs...)
         @info "Filtering candidate locations..."
         selected_pairs = []
         for (plant_name, plant_dict) in csol["Plants"]