Merge branch 'master' into stagging

README.md

@@ -43,7 +43,11 @@ JSBSim is used in a range of projects among which:
 * Machine Learning Aircraft control: [gym-jsbsim](https://github.com/galleon/gym-jsbsim)
 * [DARPA Virtual Air Combat Competition](https://www.darpa.mil/news-events/2019-10-21) where one of the AI went undefeated in five rounds of mock air combat against an Air Force fighter (see the [video on YouTube](https://www.youtube.com/watch?v=IOJhgC1ksNU)).
 
-JSBSim is also used in academic and industry research ([more than 700 citations referenced by Google Scholar](https://scholar.google.com/scholar?&q=jsbsim) as of May 2022).
+## Academic and Industry Research
+
+JSBSim is also used in academic and industry research ([more than 700 citations referenced by Google Scholar](https://scholar.google.com/scholar?&q=jsbsim) as of May 2023).
+
+In 2023 JSBSim has been featured in the article ["A deep reinforcement learning control approach for high-performance aircraft"](https://link.springer.com/article/10.1007/s11071-023-08725-y) on _Nonlinear Dynamics_, an International Journal of Nonlinear Dynamics and Chaos in Engineering Systems by Springer. The open access article is available as a PDF here [https://link.springer.com/content/pdf/10.1007/s11071-023-08725-y.pdf](https://link.springer.com/content/pdf/10.1007/s11071-023-08725-y.pdf). The work demonstrates an application of Deep Reinforcement Learning (DRL) to flight control and guidance, leveraging the JSBSim interface to MATLAB/Simulink.
 
 # User Guide
 

src/input_output/FGInputSocket.cpp

@@ -66,13 +66,13 @@ FGInputSocket::FGInputSocket(FGFDMExec* fdmex) :
 
 FGInputSocket::~FGInputSocket()
 {
-  //delete socket;
+  delete socket;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 bool FGInputSocket::Load(Element* el)
-{/*
+{
   if (!FGInputType::Load(el))
     return false;
 
@@ -87,14 +87,13 @@ bool FGInputSocket::Load(Element* el)
   if (to_upper(action) == "BLOCKING_INPUT")
     BlockingInput = true;
 
-  return true;*/
-  return false;
+  return true;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 bool FGInputSocket::InitModel(void)
-{/*
+{
   if (FGInputType::InitModel()) {
     delete socket;
     socket = new FGfdmSocket(SockPort, SockProtocol);
@@ -104,15 +103,15 @@ bool FGInputSocket::InitModel(void)
 
     return true;
   }
-*/
+
   return false;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 void FGInputSocket::Read(bool Holding)
 {
-  /*if (!socket) return;
+  if (!socket) return;
   if (!socket->GetConnectStatus()) return;
 
   if (BlockingInput)
@@ -271,7 +270,7 @@ void FGInputSocket::Read(bool Holding)
         "   info\n\r\n");
 
       } else {
-        //socket->Reply(string("Unknown command: ") + command + "\r\n");
+        socket->Reply(string("Unknown command: ") + command + "\r\n");
       }
 
       start = string_end;
@@ -285,7 +284,7 @@ void FGInputSocket::Read(bool Holding)
       else
         data.clear();
     }
-  }*/
+  }
 
 }