###### Abstract
In this issue, a new type of PTMD that uses a shape memory alloy sponge as the energy dissipating material is reported [31], and the application of the PTMD is extended to the vibration control of suspended piping systems in buildings [32]. Since viscoelastic materials are used in the conventional PTMDs [17; 18; 24] and the effectiveness of viscoelastic materials are negatively impacted by the water depth (pressure), for its underwater applications, conventional PTMD can only be applied in shallow water where the pressure is low. With the metallic porous shape memory alloy sponge whose damping performance is not impacted by water depth, the application of PTMD can be extended to deep water. In the past, there is no study on the impact of seawater on viscoelastic materials' damping effect. In this special issue, the seawater effect on the impact damping behavior of the viscoelastic material of PTMD is reported for the first time [33]. It is found that the seawater has a minimal effect on the viscoelastic materials for their damping effectiveness. This special issue also reports other types of new energy dissipation devices, such as a multi-unit particle damper [34], a nonlinear eddy current damper [35], and layered dampers [36; 37]. Furthermore, also reported in this issue are structural elements with innovative designs to dissipate energy [38; 39; 40]. In addition, this special issue also reports two research studies on the dynamic responses of a structural foundation [41] and an earth-retaining structure [42]. Though most papers in this special issue are related to passive methods, one paper reports a semi-active vibration control via magnetorheological dampers (MRDs) [43], and another two papers report active vibration controls using piezoelectric transducers [44] and inertial actuators [45], respectively. MRDs are essentially passive devices, though their damping forces can be actively adjusted via electromagnets [20]. Please note that, for active vibration control, piezoelectric transducers have quick response and wide bandwidth [46; 47; 48], however, their outputs as displacement or force are limited. On the other hand, though most inertial actuators have low bandwidth, they can deliver much larger displacement or force for active vibration control. A special novel liquid transfer active balancing system to reduce oscillations of hollow rotors for high-speed rotating machinery is presented in this issue [49]. Finally, this special issue includes one review paper on the topic of seat suspension technology [50]. In summary, the topics in the special issue include new damping materials development [37], new damper vibration modeling, novel algorithms for active vibration control [44; 45], novel passive damping methods and devices [25; 26; 27; 28; 29; 30], innovative energy dissipation devices [38; 39; 40], and an explorative characterization of materials for energy dissipation [33], among others. For the future trends of research in energy dissipation for vibration control, two avenues should be noted. One avenue points to the integrated vibration control and energy harvesting. Piezoelectric transducers [51; 52] and electromagnetic devices [53] can be used to convert vibration energy into electrical energy, reducing structural vibration while harvesting energy. The success of energy harvesting from structural vibration will lead to the second avenue for future work which is the integrated structural vibration control and health monitoring. The harvested energy that dissipates structural vibration can be used to power sensors that are used in structural health monitoring (SHM) systems. Though many advances have been made in SHM [54; 55], the limited power source is currently a major roadblock for the wide application of SHM systems [56]. It is believed that integrated structural vibration control and health monitoring with energy harvesting is an effective way to promote future SHM systems.