Read the following passage about deep-sea submersibles:
Deep-sea research submersibles operating in hadal trenches rely on two distinct structural strategies to withstand extreme hydrostatic load while maintaining neutral buoyancy. For crew accommodation, engineers utilize grade-5 titanium spherical pressure hulls, as spherical geometry distributes crushing isotropic forces evenly across the hull wall, eliminating localized shear points. Conversely, vehicle flotation cannot use trapped atmospheric air; instead, submersibles incorporate solid syntactic foam blocks composed of microscopic hollow glass microspheres embedded within rigid epoxy resin. This composite material resists high-pressure compaction while providing vital uplift because its aggregate density remains significantly lighter than surrounding seawater. Furthermore, external structural frames are fabricated from open-matrix syntactic composites that allow ambient water to flood internal voids, preventing differential pressure accumulation across chassis components.
Based on the passage, match each factual detail from the text with its accurate paraphrased restatement.
- Spherical titanium crew hulls eliminate localized shear failure.Symmetrical metallic compartments uniformly disperse multidirectional compression along the enclosure boundary.
- Syntactic foam blocks generate upward flotation in deep trenches.The composite structure provides positive lift because its total mass density is lower than the surrounding marine environment.
- Microscopic hollow glass microspheres are bound within epoxy resin.Tiny evacuated glass spheres are encased in a hardened polymer matrix to resist compression.
- Open-matrix external frames permit ambient seawater to flood interior voids.Unsealed chassis structures admit surrounding fluid into empty cavities to prevent uneven force accumulation.