Chronology of the Basalt Units Surrounding Chang’e-4 Landing Area

The Chang’e-4 (CE-4) lunar probe, the first soft landing spacecraft on the far side of the Moon, successfully landed in the Von Kármán crater on 3 January 2019. Geological studies of the landing area have been conducted and more intensive studies will be carried out with the in situ measured data. The chronological study of the maria basalt surrounding the CE-4 landing area is significant to the related studies. Currently, the crater size-frequency distribution (CSFD) technique is the most popular method to derive absolute model ages (AMAs) of geological units where no returned sample is available, and it has been widely used in dating maria basalt on the lunar surface. In this research, we first make a mosaic with multi-orbital Chang’e-2 (CE-2) images as a base map. Coupled with the elevation data and FeO content, nine representative areas of basalt units surrounding the CE-4 landing area are outlined and their AMAs are derived. The dating results of the nine basalt units indicate that the basalts erupted from 3.42 to 2.28 Ga ago in this area, a period much longer than derived by previous studies. The derived chronology of the above basalt units establishes a foundation for geological analysis of the returned CE-4 data.

A minimum transmitted load control method for shock isolation mounts with magnetorheological energy absorbers

This paper proposed a minimum transmitted load (MTL) control method for drop-induced shock isolation mounts (SIM) with magnetorheological energy absorbers (MREAs). MTL control method consists of two parts of maximum damping force (MDF) control and one part of constant acceleration (CA) control, which can make the payload stop after fully utilize MREA stroke (soft landing) with minimum transmitted load. The control algorithm of MTL control method is derived in a single-degree-of-freedom (SDOF) system. The relationship between the controllable velocity range of MTL control method and parameters of shock isolation mounts is also derived. An optimal control method selection criterion between Bingham number (BN) control method and MTL control method is developed. The performance of MTL control method and selection criterion are shown by applying to the SIM system with variable drop velocities and system parameters. Results shows that MTL control method has the minimum transmitted load and the selection criterion is feasible.

Enabling Continuous Commissioning through Building Management Systems

<p>The use and application of energy efficient technologies within new and existing buildings is a growing global trend. However, if they aren’t being commissioned, controlled and operated in an efficient way, are they really making a valid impact on the energy efficiency of our buildings? Building Management Systems (BMS) are installed within large scale non-residential buildings to control and govern the operation of Heating Ventilation and Air-Conditioning systems (HVAC). BMS monitor and process large amounts of data during their day-to-day operation, while the potential usefulness of BMS to implement energy optimising strategies is typically left un-utilised. There is a growing need to reduce building energy demand. Continuous Commissioning (CCx) may offer the potential to achieve this reduction through the ongoing or periodical assessment of building HVAC operation. As CCx is a cyclic process, and because BMS already monitor and process data in their day-to-day operations, they offer a potential, low overhead means of running CCx processes in buildings. This thesis reports a research project which explores this opportunity to assess and improve building operating efficiency by identifying what data and functional capabilities are required of a BMS to facilitate Continuous Commissioning. A systematic assessment of existing research and standards has highlighted a gap in industry knowledge on the specification of data required to implement CCx assessments to HVAC. There was also no definition of what BMS capabilities were important to the Continuous Commissioning process. These research gaps inspired five secondary research questions around which a mixed-method survey was developed and implemented to bridge the gap between BMS and CCx. The research methodology integrated a standard questionnaire and the Delphi method to explore user perceptions and develop a consensus of BMS requirements. Three survey rounds were distributed to New Zealand based industry experts. Each round informed the following round, with an element of feedback provided through the compilation of the previous round’s responses. This process enabled the industry experts to agree or disagree with the proposed consensus or provide an alternative insight to the questions asked. The results of the surveys were compiled to establish a definition of the top five CCx assessments applied to typical HVAC systems, data point trending requirements and BMS functions important to facilitating Continuous Commissioning. These findings were used to create a guideline for specifying BMS to facilitate Continuous Commissioning and create a soft landing for assessing HVAC during the operation phase of a building’s life. The outcome of this research bridges the gap between the specification of Building Management Systems and the requirements of the Continuous Commissioning process.</p>

Enabling Continuous Commissioning through Building Management Systems

<p>The use and application of energy efficient technologies within new and existing buildings is a growing global trend. However, if they aren’t being commissioned, controlled and operated in an efficient way, are they really making a valid impact on the energy efficiency of our buildings? Building Management Systems (BMS) are installed within large scale non-residential buildings to control and govern the operation of Heating Ventilation and Air-Conditioning systems (HVAC). BMS monitor and process large amounts of data during their day-to-day operation, while the potential usefulness of BMS to implement energy optimising strategies is typically left un-utilised. There is a growing need to reduce building energy demand. Continuous Commissioning (CCx) may offer the potential to achieve this reduction through the ongoing or periodical assessment of building HVAC operation. As CCx is a cyclic process, and because BMS already monitor and process data in their day-to-day operations, they offer a potential, low overhead means of running CCx processes in buildings. This thesis reports a research project which explores this opportunity to assess and improve building operating efficiency by identifying what data and functional capabilities are required of a BMS to facilitate Continuous Commissioning. A systematic assessment of existing research and standards has highlighted a gap in industry knowledge on the specification of data required to implement CCx assessments to HVAC. There was also no definition of what BMS capabilities were important to the Continuous Commissioning process. These research gaps inspired five secondary research questions around which a mixed-method survey was developed and implemented to bridge the gap between BMS and CCx. The research methodology integrated a standard questionnaire and the Delphi method to explore user perceptions and develop a consensus of BMS requirements. Three survey rounds were distributed to New Zealand based industry experts. Each round informed the following round, with an element of feedback provided through the compilation of the previous round’s responses. This process enabled the industry experts to agree or disagree with the proposed consensus or provide an alternative insight to the questions asked. The results of the surveys were compiled to establish a definition of the top five CCx assessments applied to typical HVAC systems, data point trending requirements and BMS functions important to facilitating Continuous Commissioning. These findings were used to create a guideline for specifying BMS to facilitate Continuous Commissioning and create a soft landing for assessing HVAC during the operation phase of a building’s life. The outcome of this research bridges the gap between the specification of Building Management Systems and the requirements of the Continuous Commissioning process.</p>

Deep Reinforcement Learning-Based Accurate Control of Planetary Soft Landing

Planetary soft landing has been studied extensively due to its promising application prospects. In this paper, a soft landing control algorithm based on deep reinforcement learning (DRL) with good convergence property is proposed. First, the soft landing problem of the powered descent phase is formulated and the theoretical basis of Reinforcement Learning (RL) used in this paper is introduced. Second, to make it easier to converge, a reward function is designed to include process rewards like velocity tracking reward, solving the problem of sparse reward. Then, by including the fuel consumption penalty and constraints violation penalty, the lander can learn to achieve velocity tracking goal while saving fuel and keeping attitude angle within safe ranges. Then, simulations of training are carried out under the frameworks of Deep deterministic policy gradient (DDPG), Twin Delayed DDPG (TD3), and Soft Actor Critic (SAC), respectively, which are of the classical RL frameworks, and all converged. Finally, the trained policy is deployed into velocity tracking and soft landing experiments, results of which demonstrate the validity of the algorithm proposed.