Unit Mass Research Articles

Retrieval operations of derelict fishing gears give insight on the impact on marine life

Abandoned, lost and discarded fishing gear (ALDFG), significantly impacts marine ecosystems and biodiversity by incidental capture known as ghost fishing. Such impacts were quantified during the Norwegian Directorate of Fisheries' annual ALDFG cleanup operation in September 2023 by examining the characteristics of retrieved ALDFG and recording the taxonomically sorted catch abundance and biomass. A total of 307 specimens equaling 382 kg of biomass were caught in the recovered gillnets and king crab pots. Gillnets exhibited a 27.3 % greater catch abundance and 50.3 % higher biomass per ALDFG unit mass compared to king crab pots. Margalef, Menhinick, Simpson, Shannon, and Pielou diversity indices showed a more pronounced impact on species richness and biodiversity associated with recovered gillnets. This study introduces an approach to assess the impact of ghost fishing on ecosystems and biodiversity through ALDFG retrieval operations, instrumental in developing estimates of the total ghost fishing capture by ALDFG.

The Kantorovich-Wasserstein distance for spatial statistics: The Spatial-KWD library

In this paper we present Spatial-KWD, a free open-source tool for efficient computation of the Kantorovich-Wasserstein Distance (KWD), also known as Earth Mover Distance, between pairs of binned spatial distributions (histograms) of a non-negative variable. KWD can be used in spatial statistics as a measure of (dis)similarity between spatial distributions of physical or social quantities. KWD represents the minimum total cost of moving the “mass” from one distribution to the other when the “cost” of moving a unit of mass is proportional to the euclidean distance between the source and destination bins. As such, KWD captures the degree of “horizontal displacement” between the two input distributions. Despite its mathematical properties and intuitive physical interpretation, KWD has found little application in spatial statistics until now, mainly due to the high computational complexity of previous implementations that did not allow its application to large problem instances of practical interest. Building upon recent advances in Optimal Transport theory, the Spatial-KWD library allows to compute KWD values for very large instances with hundreds of thousands or even millions of bins. Furthermore, the tool offers a rich set of options and features to enable the flexible use of KWD in diverse practical applications.

I-section steel columns strengthened by wire arc additive manufacturing - concept and experiments

Wire arc additive manufacturing (WAAM) is a method of metal 3D printing which, when strategically combined with traditional methods of manufacture, has the potential to make a significant impact on the construction sector. To illustrate this potential, an experimental investigation into the flexural buckling response of 15 hot-rolled I-section columns, strengthened by WAAM, has been undertaken and is presented herein. The WAAM material was added at the flange tips and distributed non-uniformly along the member length. Complementary tensile coupon tests on the I-section and WAAM steel material were also carried out. 3D laser scanning was employed to determine the geometry and global geometric imperfections of all specimens, while digital image correlation measurements were taken to provide a detailed insight into the surface deformation characteristics of the specimens during testing. The WAAM stiffeners provided three mechanisms of strengthening: (1) increased cross-sectional area and second moment of area, (2) enhanced local buckling capacity and (3) a more favourable residual stress pattern. Disproportionately high increases in axial capacity of between 17% and 54% for relatively modest increases of mass between 2% and 26% (of the weight of the strengthened I-section column) were achieved, demonstrating, for the first time, the substantial benefits in terms of enhanced structural efficiency and material savings, that can be realised by the combination of WAAM with traditional manufacturing methods. In the best case, the efficiency of the WAAM material (in terms of increase in load-bearing capacity per unit mass) was almost eight times that of the bare steel section. The described hybrid manufacturing concept can be employed to improve the performance and reduce the environmental impact of structures and could be a game changer in both new construction and the rehabilitation of existing infrastructure.

Modal Response Improvement of Periodic Lattice Materials with a Shear Modulus-Based FE Homogenized Model.

Lattice materials are widely used in industries due to their designable capabilities of specific stiffness and energy absorption. However, evaluating the mechanical response of macroscopic lattice structures can be computationally expensive. Homogenization-based multi-scale analysis offers an efficient approach to address this issue. To achieve a simpler, while precise, homogenization, the authors proposed an equidistant segmentation (ES) method for the measurement of the effective shear modulus. In this method, the periodic boundary conditions (PBCs) are approximated by constraining the lateral displacement of nodes between parallel layers of periodic cells. The validations were applied to three typical lattice topologies: body-centered cubic (BCC) lattices, gyroid-, and primitive-triply periodic minimal surface (TPMS) lattices, to predict and compare their anti-vibration capacities. The results demonstrated the rationality and the promising precision of the multi-scale-based equivalent modal analysis through the proposed method and that it eliminated the geometric limitation of lattices with diverse frameworks. Overall, a higher anti-vibration capacity of TPMS was observed. In the study, the authors examined the influence of the relative densities on the balance between the anti-vibration capacity and loading capacity (per unit mass) of the TPMS topologies. Specifically, the unit mass of the TPMS with lower relative densities was able to resist higher frequencies, and the structures were dominated by the anti-vibration capacity. In contrast, a higher relative density is better when emphasizing the loading capacity. These findings may provide notable references to the designers and inform the selection of lattice materials for various industrial applications.

Dense Oil in Water Emulsions using Vortex-Based Hydrodynamic Cavitation: Effective Viscosity, Sauter Mean Diameter, and Droplet Size Distribution.

Vortex-based hydrodynamic cavitation offers an effective platform for producing emulsions. In this work, we have investigated characteristics of dense oil in water emulsions with oil volume fractions up to 60% produced using a vortex-based cavitation device. Emulsions were prepared using rapeseed oil with oil volume fractions of 0.15, 0.3, 0.45, and 0.6. For each of these volume fractions, the pressure drop as a function of the flow rate of emulsions through the cavitation device was measured. These data were used for estimating the effective viscosity of the emulsions. The droplet size distribution of the emulsions was measured using the laser diffraction technique. The influence of the number of passes through the cavitation device on droplet size distributions and the Sauter mean diameter was quantified. It was found that the Sauter mean diameter (d32) decreases with an increase in the number of passes as n-0.2. The Sauter mean diameter was found to be almost independent of oil volume fraction (αo) up to a certain critical volume fraction (αoc). Beyond αoc, d32 was found to be linearly proportional to a further increase in oil volume fraction. As expected, the turbidity of the produced emulsions was found to be linearly proportional to the oil volume fraction. The slope of turbidity versus oil volume fraction can be used to estimate the Sauter mean diameter. A suitable correlation was developed to relate turbidity, volume fraction, and Sauter mean diameter. The droplet breakage efficiency of the vortex-based cavitation device for dense oil in water emulsions was quantified and reported. The breakage efficiency was found to increase linearly with an increase in oil volume fraction up to αoc and then plateau with a further increase in the oil volume fraction. The breakage efficiency was found to decrease with an increase in energy consumption per unit mass (E) as E-0.8. The presented results demonstrate the effectiveness of a vortex-based cavitation device for producing dense oil in water emulsions and will be useful for extending its applications to other dense emulsions.

Gamma-ray, fast neutron and charged particle shielding performance of 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 glass system

Gamma-ray, fast neutron and charged particle shielding characteristics of Dy3＋ activated glasses with composition 15Li2O-25BaO-(40-x)B2O3-20P2O5-xDy2O3 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%) are analyzed in a wide incident energy for the first time. For gamma-ray shielding analysis, mass attenuation coefficient (MAC), mass energy absorption coefficient (μen), linear attenuation coefficient (LAC), mean free path (MFP), half-value layer (HVL), atomic cross-section (ACS), electronic cross-section (ECS), effective atomic number (Zeff), equivalent atomic number (Zeq), effective conductivity (Ceff), effective electron density (Neff), buildup factors (EABF and EBF), and kinetic energy released per unit mass of the absorbing material (KERMA) are calculated by using Phy-X/PSD and PAGEX softwares. For fast neutrons, fast neutron removal cross-section (FNRCS) is computed for all glass samples. For charged particle shielding analysis, mass stopping power (MSP), projected range (Rp), radiation yield (Ry), Zeff and Neff are computed using SRIM, ESTAR and PAGEX softwares. It is found that the glasses with increasing Dy3＋ have higher shielding potential. This suggests that the LBPDy1.0 sample has a potential use as shielding material for various applied fields.

Mitochondrial ATP generation is more proteome efficient than glycolysis.

Metabolic efficiency profoundly influences organismal fitness. Nonphotosynthetic organisms, from yeast to mammals, derive usable energy primarily through glycolysis and respiration. Although respiration is more energy efficient, some cells favor glycolysis even when oxygen is available (aerobic glycolysis, Warburg effect). A leading explanation is that glycolysis is more efficient in terms of ATP production per unit mass of protein (that is, faster). Through quantitative flux analysis and proteomics, we find, however, that mitochondrial respiration is actually more proteome efficient than aerobic glycolysis. This is shown across yeast strains, T cells, cancer cells, and tissues and tumors in vivo. Instead of aerobic glycolysis being valuable for fast ATP production, it correlates with high glycolytic protein expression, which promotes hypoxic growth. Aerobic glycolytic yeasts do not excel at aerobic growth but outgrow respiratory cells during oxygen limitation. We accordingly propose that aerobic glycolysis emerges from cells maintaining a proteome conducive to both aerobic and hypoxic growth.

Climatology of gravity wave activity based on two Martian years from ACS/TGO observations

Context. Gravity waves redistribute energy and momentum between the lower and upper atmosphere, thus providing vertical coupling between layers, and they affect the state, dynamics, and variability of the upper atmosphere. The statistics of gravity wave activity on Mars is poorly explored but is required in order to characterize the atmospheric circulation and to constrain numerical models. Aims. We present the gravity wave statistics accumulated over two Martian years: from the second half of Martian year 34 to the middle of Martian year 36 (May 2018 to February 2022). The statistics includes seasonal and latitude distributions of the wave potential energy and drag, serving to represent the wave activity and impact on the atmospheric dynamics. Methods. The observations were performed by the middle- and near-infrared spectrometers of the Atmospheric Chemistry Suite on board the ExoMars Trace Gas Orbiter. The temperature profiles we obtained independently from both channels during simultaneous measurements show a good agreement, thus providing verification and enhancing confidence in the data. The gravity wave parameters included amplitudes of temperature fluctuations, potential energy per unit mass, and wave drag. These parameters were retrieved at altitudes up to 160 and 100 km from the middle- and near-infrared channels, respectively. Results. A comparison of the data obtained during the global dust storm of Martian year 34 with the corresponding period of Martian year 35 without a storm revealed a reduction of wave activity in mid-latitudes, which is in agreement with previous observations, and enhancement in the polar regions of the southern hemisphere, which was not predicted by simulations with a high-resolution circulation model.

Numerical investigation of the mechanical properties of lattice structures inspired from polycrystalline materials

In this work, polycrystalline-like lattice structures that are inspired by the geometry of polycrystalline materials are designed. They are generated by filling periodic lattice structures into a Voronoi diagram. Then, finite element analyses of two periodic and eight polycrystalline-like lattice structures are performed to compare their mechanical properties. The numerical results show that polycrystalline-like lattice structures consisting of anisotropic rectangular X-type periodic unit cells are isotropic at the macroscale. Moreover, they have a higher specific stiffness and specific strength than periodic lattice structures under compression. Then, the energy absorption capability is investigated. Five energy absorption indicators (energy absorption, energy absorption per unit volume, specific energy absorption per unit mass, crush stress efficiency, and plateau stress) reveal that polycrystalline-like lattice structures are better energy absorption structures. Furthermore, the defect sensitivity of missing struts is discussed. The findings of this work offer a new route for designing novel lattice structures.

Experimental Study on Flame Chemical Composition of Coal and Ammonia Gas-Solid Jet in Flat Flame Burner.

Ammonia as a fuel to partially or completely replace fossil fuels is one of the effective ways to reduce carbon dioxide, and the research on ammonia coal cocombustion is of great significance. The combustion characteristics of ammonia are very different from those of pulverized coal, resulting in the ignition and emission characteristics of ammonia and pulverized coal gas flow that is different from traditional pulverized coal flame. In this paper, the effect of pulverized coal concentration in coal and ammonia mixed combustion jet on the ignition distance and gas-phase components at different positions of the jet flame were studied experimentally on the flat flame burner, and the conditions of ignition and ignition stability of coal and ammonia gas-solid fuel were expounded. It was found that the ammonia mixed with pulverized coal changed the temperature field of the flat flame burner and therefore the ignition characteristics of the jet were changed. The ignition delay time at the same jet speed was positively correlated with the pulverized coal concentration, but when the pulverized coal concentration continued to decrease, the influence on the ignition delay time gradually became smaller. The composition of coal ammonia gas-solid fuel changed the heat transfer path and share during combustion, and finally, the flame temperature was negatively correlated with the concentration of pulverized coal. Therefore, the reduction of the pulverized coal concentration was conducive to the stable combustion of coal ammonia mixed fuel. When HAB = 100 mm, the conversion rate of fuel N to NOx per unit mass of coal ammonia mixture increased with the increase of pulverized coal concentration. The NOx production amount first increased and then decreased with the increase of pulverized coal concentration, and the amount of N2O and NO2 decreased rapidly with the increase of HAB. The proportion of NOx in NO exceeded 94%, which was conducive to achieving low nitrogen combustion of coal and ammonia gas-solid fuel. In general, the O2 concentration in the ammonia coal jet flame decreased, the flue gas temperature, and NOx and CO generation increased after mixing ammonia, and the optimal pulverized coal concentration in this experiment was 0.41 kgc/kga (mass ratio of pulverized coal to the sum of N2 and NH3).

Nanographene oxide modified fiber reinforced cementitious composites: Thermomechanical behaviour, environmental analysis and microstructural characterization

A novel fiber reinforced cementitious composites was developed by incorporating microencapsulated phase change materials (PCMs) and nanographene oxide (NGO) to enhance the composites’ thermal properties without compromising the compressive strength. Regarding the thermo-mechanical properties, with the addition of NGO, while mechanical properties improve, thermal mass increases and the heat storage ability of the produced composite material enhances. In this situation; it can be interpreted that it will be possible to benefit more from the energy stored by PCMs, as the energy required to change the temperature of the unit mass of the material will decrease. The environmental impact assessment has also revealed that CO2 emissions from production increase with the use of PCMs. However, it has been determined that the addition of NGOs will make a positive contribution to the life cycle, as CO2 emissions resulting from cement will decrease. In conclusion, a novel fiber reinforced composite with enhanced thermal and mechanical properties by combining PCMs and NGO has shown a great potential for environmentally friendly buildings with the integration of structure, energy conservation and long term durability.

The impact of selenium yeast and vitamin E in blood profile and egg production of laying hens at the end of egg production period

This study investigated the effects of selenium yeast and vitamin E supplementation on hematological parameters, egg production, and quality in laying hens aged beyond 94 weeks. The experiment adhered to ethical regulations and employed a Completely Randomized Design Dietary treatments included a basal diet (T0), or a basal diet supplemented with 0.450 mg selenium yeast and 100 mg vitamin E (T1), 0.675 mg selenium yeast and 100 mg vitamin E (T2), 0.450 mg selenium yeast and 200 mg vitamin E (T3), 0.675 mg selenium yeast and 200 mg vitamin E per kg diet (T4). There were 125 hens divided in five treatments and five replicates that contained five hens per replicate. Hematological parameters, egg production, and egg quality were determined. The T4 treatment reduced red blood cell counts (P<0.05), potentially impacting erythropoiesis. The T3 treatment increased lymphocyte content and decreased heterophil/lymphocyte ratio (P<0.05), which concurs with an increase in egg weight, egg mass, and Haugh Unit, and decreased feed conversion ratio (P<0.05). Thus, this study demonstrated that incorporating these supplements with the specified dosage (0.450 mg selenium yeast and 200 mg vitamin E per kg diet) in aged laying hens can enhance productivity and egg quality at the end of the production cycle.

Quality control of allergen products with mass spectrometry part I: Positioning within the EU regulatory framework.

Mass spectrometry (MS) has advanced greatly and many of its applications are ready for utilization within regulatory procedures and could significantly contribute to overcome challenges in standardization of allergen products. It seems sensible to discuss MS within the regulatory framework, before addressing technical questions. While the application to purified proteins is well established from product development to manufacturer's release analytics, its application to complex products such as allergen products is still under development. It needs to be determined where it can complement or replace established methods or where MS offers limited improvement. Despite its technical appeal and versatility, currently MS is mentioned in regulatory guidelines only as one possible measurement method. For example, no specific MS method is given in the European Pharmacopoeia. We discuss applications of MS within the EU regulatory framework. This includes their advantages and disadvantages and their positioning between research, characterization, manufacturer's release analytics and official batch testing. We discuss the qualitative detection of single and multiple allergens as proof of identity, qualitative to semi-quantitative protein profiles for batch to batch consistency testing, and quantification of allergens to state mass units of allergens. MS may also facilitate standardization of allergen products, reference products and reference standards.

Determining conditions for providing maximum traction efficiency of tractor as part of a soil tillage unit

This study aims to investigate the operation of a tractor as part of the tillage unit on the basis of analysis of its interaction with the supporting surface and the correlation between the mass of the tractor and tool. The classic approach to determining the efficiency factor does not take into account the extensive system of power take-off shafts and the extent of their use in combined tillage units. To solve the related problem, a mathematical apparatus was built in the study, which makes it possible to determine the rational ratio between the traction force of a tractor and the mass of the tillage unit. Underlying the methodological basis of the work is the generalization and analysis of the study of traction indicators of the tractor as part of the tillage unit. Empirical models of unit operation were constructed by employing the basic principles of the system approach and analysis of technical systems. When improving the methodology of research using the method of partial accelerations and our devised procedures, it was possible to significantly reduce the time without compromising the quality of results. The maximum traction efficiency for John Deere 8R series tractors as part of the tillage unit was determined, ηTmax=0.719, as well as the conditions for its provision. The traction efficiency for tractors with wheel formula 4K2, mass Gim=6–10 t, with power consumption from 60 % to 80 % was determined; it is 0.58–0.64. The results of the study make it possible to obtain a new solution to the scientific problem of ensuring the maximum traction efficiency of the tractor as part of the tillage unit, based on the rational ratio between the traction force of the tractor and the weight of the machine-tractor unit. The proposed system approach could be used to justify the layout of units and recommendations regarding their modes of operation in the case of instability of operating mass and traction force

3D-printed thermoplastic polyurethane/polyvinylidene fluoride gradient stiffness and hierarchical cellular structures with tailored energy absorption behavior

Currently, designing materials and structures is the main means of improving their energy-absorption properties; however, optimization methods based on structural design can only be applied to specific structures. In this study, two optimization methods of energy-absorbing structures (EASs) are proposed from the material system and manufacturing method for fabricating gradient stiffness and hierarchical cellular structures, respectively. The gradient stiffness structure was prepared using different ratios of thermoplastic polyurethane (TPU)/polyvinylidene fluoride (PVDF) filaments in different locations in the EAS. The gradient stiffness structure exhibited energy-absorption behavior corresponding to the strength of the printed material; this behavior decreased in the order of material strength from low to high, thus achieving controlled yield deformation behavior. Hierarchical honeycomb structures were prepared by combining three-dimensional (3D) printing with supercritical CO2 foaming technology, which facilitated the simultaneous formation of both centimeter and micron-scale cellular structures. When the PVDF content was 30%, the average cellular size of the microcellular structure was only 3 μm, and the prepared hierarchical honeycomb structures exhibited higher energy-absorption efficiencies compared with the general honeycomb structure. The energy absorption per unit mass values in three different compression directions of the hierarchical honeycomb structures were 152.75%, 67.33%, and 56.91% higher, respectively, than that of the TPU honeycomb without foaming. Therefore, the gradient stiffness and hierarchical honeycomb structures prepared from TPU/PVDF blends have various applications in energy absorption, personal protection, and transportation.

Morphological, Structural and Optical Properties of Er3+-Doped SiO2-TiO2 Nanofiber

Morphological, Structural and Optical Properties of Er3+-Doped SiO2-TiO2 Nanofiber

The Effects of Manufacturing Techniques on the Mechanical Performance of an Auxetic Structure Manufactured by Fused Filament Fabrication and Multijet Fusion Processes

Additive manufacturing is increasingly becoming potential for short‐run part production. The aim of this work is to explore the mechanical properties of a hybrid auxetic structure fabricated by multijet fusion (MJF) and fused filament fabrication (FFF). The experimental measurements indicate that robust specimens with high‐dimensional accuracy are successfully achieved using MJF process. In the case of the FFF process, the walls–walls and walls–cylinders areas (connecting areas) suffer large pores, indicating poor printing quality. The 3D printed specimens via FFF process reveal smooth plateau stress, while plateau stress with high peaks is observed when the MJF specimens are compressed along the Y‐axis. Moreover, specimens manufactured by the MJF process reveal the highest specific energy absorption (SEA) per unit volume and per unit mass. The calculated values of SEA are 2.1 and 2.5 J g−1 (for specimens fabricated by MJF) in which they significantly outperform the SEA (0.495 and 0.480 J g−1) of those manufactured by the FFF process. Furthermore, the trend of auxetic features (negative Poisson's ratio) has not been affected by the manufacturing processes. This study sheds light on the influence of fabrication methods on the mechanical properties of cellular materials especially their ability to absorb energy.

Carbon fractions in wood for estimating embodied carbon in the built environment

Determining wood carbon (C) fractions (CFs)—or the concentration of elemental C in wood on a per unit mass basis—in harvested wood products (HWP) is vital for accurately accounting embodied C in the built environment. Most estimates of embodied C assume that all wood-based building material is comprised of 50 % C on a per mass basis: an erroneous assumption that emerges from the literature on tree- and forest-scale C estimation, which has been shown to lead to substantial errors in C accounting. Here, we use published wood CF data from live trees, alongside laboratory analyses of sawn lumber, to quantify generalizable wood CFs for HWPs. Wood CFs in lumber average 51.7 %, deviating significantly from a 50 % default wood CF, as well as from CFs in live wood globally (which average 47.6 % across all species, and 47.1 % in tree species not typically employed in construction). Additionally, the volatile CF in lumber—i.e., the quantity of C lost upon heating of wood samples, but often overlooked in C accounting—is lower than the volatile CF in live wood, but significantly >0 % suggesting that industrial lumber drying processes remove some, but not all, of volatile C-based compounds. Our results demonstrate that empirically-supported wood CFs for construction material can correct meaningful systematic biases when estimating C storage in the built environment.

Turbulent spot formation in stably stratified three-dimensional Yukawa liquids

A plane-Couette flow (PCF) is considered in a stably stratified three-dimensional (3D) Yukawa liquid, perturbed initially with a finite amplitude 3D perturbation. Stable stratification in density is achieved by subjecting the medium to external gravity. We demonstrate turbulent spot formation in a stably stratified PCF. The dynamics of the system is shown to depend upon the value of κ, which is associated with the range of interaction. We have performed “first principles” classical 3D molecular dynamics (MD) simulations for “hypergravity” (1.3g0, g0 is Earth's gravitational force for unit mass in our normalized unit) and “milligravity” (9×10−3g0) cases for κ, 1.0 and 4.0, respectively. We extract relevant fluid quantities from MD data. For the hypergravity case, when the system is evolved in time under stable stratification, the kinetic energy is observed to deposit in the lower wave vectors (Kx, Kz), leading to “inverse cascade” in the plane perpendicular to the direction of stratification. As a result, we observe large-scale structure formation in velocity and streamwise vorticity fields. Nucleation of velocity streak is observed for the first time in the stably stratified case in our simulation. The coherent structures in the velocity and streamwise vorticity fields are found to sustain for longer period of time for the stably stratified cases as compared to the unstratified case. For the milligravity case, the large-scale dynamics is observed to enhance. Unlike unstratified PCF, a background flow in Y-averaged streamwise fluid velocity field is observed for the stably stratified case. We believe that our results using “first principles” classical MD simulations on subcritical turbulence in stably stratified Yukawa liquid, may have ramifications to wider class turbulence problems. Published by the American Physical Society 2024

An analytical vibration model of a one-dimensional two-stage periodic isolation system for the broadband vibration suppression of an underwater glider

Periodic isolation system is effectively applied in broadband vibration control. To further enhance the broadband vibration attenuation effect, the paper proposes a two-stage periodic isolation system for an underwater glider. The analytical model of the one-dimensional two-stage periodic isolation system is developed through the multi-degree of freedom spring mass model method. For illustrating the superiority of the proposed two-stage periodic isolator, the force transmission ratio and the wave propagation constant of the SDOF isolator, the single-stage periodic isolator, and the two-stage periodic isolator are calculated and compared. In order to obtain the dynamic parameter influences on the vibration isolation performances as the design guidelines of the two-stage periodic isolator, the parametrical study is carried out based on the analytical model. Furthermore, a two-stage periodic isolator is designed for an underwater glider. The application effect of the two-stage periodic isolator is investigated through analytical modeling and finite element method, comparing to the single-stage periodic isolator. The research results from the analytical models show the proposed two-stage periodic isolator could strength the broadband vibration suppression. The parametrical study results demonstrate the vibration attenuation bandgap and attenuation amount are greatly influenced by the designed dynamic parameters, such as the mass unit and the spring unit of the periodic isolator, the intermediate mass of the two-stage isolator, and the number of the periodic cells. In application study of an underwater glider, the finite element results verify that the two-stage periodic isolator has more vibration attenuation effect than the single-stage periodic isolator. The vibration isolation assessment according to the proposed analytical model gives good predictive performance before the finite element model verification.