Safe deep reinforcement learning in diesel engine emission control

A deep reinforcement learning application is investigated to control the emissions of a compression ignition diesel engine. The main purpose of this study is to reduce the engine-out nitrogen oxide ( N O x ) emissions and to minimize fuel consumption while tracking a reference engine load. First, a physics-based engine simulation model is developed in GT-Power and calibrated using experimental data. Using this model and a GT-Power/Simulink co-simulation, a deep deterministic policy gradient is developed. To reduce the risk of an unwanted output, a safety filter is added to the deep reinforcement learning. Based on the simulation results, this filter has no effect on the final trained deep reinforcement learning; however, during the training process, it is crucial to enforce constraints on the controller output. The developed safe reinforcement learning is then compared with an iterative learning controller and a deep neural network-based nonlinear model predictive controller. This comparison shows that the safe reinforcement learning is capable of accurately tracking an arbitrary reference input while the iterative learning controller is limited to a repetitive reference. The comparison between the nonlinear model predictive control and reinforcement learning indicates that for this case reinforcement learning is able to learn the optimal control output directly from the experiment without the need for a model. However, to enforce output constraint for safe learning reinforcement learning, a simple model of system is required. In this work, reinforcement learning was able to reduce N O x emissions more than the nonlinear model predictive control; however, it suffered from slightly higher error in load tracking and a higher fuel consumption.

Cold Climate Impact on Air-Pollution-Related Health Outcomes: A Scoping Review

In cold temperatures, vehicles idle more, have high cold-start emissions including greenhouse gases, and have less effective exhaust filtration systems, which can cause up to ten-fold more harmful vehicular emissions. Only a few vehicle technologies have been tested for emissions below -7 °C (20 °F). Four-hundred-million people living in cities with sub-zero temperatures may be impacted. We conducted a scoping review to identify the existing knowledge about air-pollution-related health outcomes in a cold climate, and pinpoint any research gaps. Of 1019 papers identified, 76 were selected for review. The papers described short-term health impacts associated with air pollutants. However, most papers removed the possible direct effect of temperature on pollution and health by adjusting for temperature. Only eight papers formally explored the modifying effect of temperatures. Five studies identified how extreme cold and warm temperatures aggravated mortality/morbidity associated with ozone, particles, and carbon-monoxide. The other three found no health associations with tested pollutants and temperature. Additionally, in most papers, emissions could not be attributed solely to traffic. In conclusion, evidence on the relationship between cold temperatures, traffic-related pollution, and related health outcomes is lacking. Therefore, targeted research is required to guide vehicle regulations, assess extreme weather-related risks in the context of climate change, and inform public health interventions.

Acoustic method for measuring the sound speed of gases over small path lengths

Acoustic "phase shift" methods have been used in the past to accurately measure the sound speed of gases. In this work, a phase shift method for measuring the sound speed of gases over small path lengths is presented. We have called this method the discrete acoustic wave and phase detection (DAWPD) method. Experimental results show that the DAWPD method gives accurate (+/-3.2 ms) and predictable measurements that closely match theory. The sources of uncertainty in the DAWPD method are examined and it is found that ultrasonic reflections and changes in the frequency ratio of the transducers (the ratio of driving frequency to resonant frequency) can be major sources of error. Experimentally, it is shown how these sources of uncertainty can be minimized.

Psychosocial care in malignant diseases of childhood: organizational and structural implications

The desirable level of psychosocial care for the malignant diseases of childhood will not occur spontaneously due to the complexity of the treatment, the numerous skills and specialties involved, and the predictably high level of parental and child needs. A philosophy of total care will require careful and explicit formulation. Once the philosophy is established, the organization and its components must structure the care in such a manner as to assure delivery of total medical-psychosocial management. Specific methods can be incorporated which will support the care deliverers who, in turn, provide the care for the nuclear family unit. Such methods may include parent group meetings, care conference rounds, and emotional-psychologic management conferences as discussed.

A case of somatic expression of family and environmental stress

A child's behavior is caused by many factors. Some are "inside" the child, such as neurons and glands, memories and motivations. "Outside" the child are factors such as his parents, his siblings, his family's socioeconomic status, his house, his school, the hue of his skin, television, and many others.

The major theoretical systems in pediatrics and child psychiatry have always been concerned with the influence of both the internal and the external factors upon the development of the child. Particular emphasis has been put, in theory, on the importance of the family and the way the child, an organism with biologic and psychologic needs, negotiates those needs within the nurturing and socializing unit called the family.

The techniques of intervention which have been developed by pediatricians and child psychiatrists have been aimed almost entirely at the child as a separate organism. Though the theories have taken account of the importance of the family in the child's development and behavior, the techniques used to help the child have not.

Pediatricians acknowledge the significance of the family in the management of a child's illness, yet traditionally they examine the child but talk with the parents, mostly the mother.

A team of pediatricians and child psychiatrists at the Philadelphia Child Guidance Clinic and the Children's Hospital of Philadelphia have joined to explore the influence of the family in the development of psychosomatic and psychogenic symptoms in children and in the management of pediatric illness. Their researches in psychosomatic syndromes, supported by an NIMH grant (#21336-02), have been described in the bibliography at the end of the third article.

The three papers which follow illustrate how includ ing the family in the field of observation leads to a richer way of understanding and treating children's illnesses. —Salvador Minuchin, M.D.