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We present PneuSeries, a series of modularized inflatables where their inflation and deflation are propagated in-between stage by stage to form various shapes. The key component of PneuSeries is the bidirectional check valve that passively regulates the air flowing in/out from/to adjacent inflatables, allowing each of the inflatables to be inflated/deflated one by one through serial propagation. The form of the inflatable series thus is programmed by the sequential operations of a pump that push/pull the air in/out. In this paper, we explored the design of PneuSeries and implemented working prototypes as a proof of concept. In particular, we built PneuSeries with (1) modularized cubical, cuboidal, tetrahedral, prismatic, and custom inflatables to examine their shape forming, (2) fast assembly connectors to allow quick reconfiguration of the series, and (3) folding mechanism to reduce irregularity of the shrunken inflatables. We also evaluated the inflating and deflating time and the flow rate of the valve for simulating the inflating and deflating process and display the steps and time required to transform in our software. Finally, we demonstrate example objects that show the capability of PneuSeries and its potential applications.

Optical illusions have been brought into recent video games to enhance gaming experiences. However, a large corpus of optical illusions remains unused, while few games incorporate illusions seamlessly. To mitigate the gap, we propose a workflow to guide game designers in applying optical illusions to their video games, i.e., in making more illusion games. In particular, our workflow consists of 5 stages: (1) choosing a game object, (2) searching for a matching illusion, (3) selecting an illusion mechanic, (4) integrating the selected illusion into the game, and (5) optionally revealing the illusion. To facilitate our workflow, we provide a tag database with 163 illusions that are labeled by their in-game visual elements and desired effects. We also provide example editing interfaces of 6 illusions for game designers. We walk through our workflow and showcase 6 resulting illusion games. We implemented these 6 games (with and without illusion) and conducted a 12-participant study to gain a preliminary understanding of how illusions enhance gaming experiences. To evaluate our workflow, we invited 6 game designers and 6 experienced players to follow our workflow and design their own illusion games, where 3 experienced game designers completed 2-week in-depth developments. We report their games, qualitative feedback and discuss reflection on our workflow, database and editing interfaces.

We present TexelBlocks, modular blocks that dynamically change their surfaces to support rich physical interactions. The core component of each block is a motorized crawler belt with a set of material patches attached to it, allowing each of the TexelBlocks to change their surface independently and be concatenated into flat surfaces of various sizes. We implemented a working system that controls 24 TexelBlocks to form 6 × 4 dynamic surfaces. With the working prototype, we developed five applications such as context-aware surface adaptation, real-time tactile feedback, immersive storytelling with dynamic background, real-time embodied platform game, and a surface-changing board game to demonstrate rich physical interactions of dynamic surfaces.

We present Impossible Staircase, a real-walking virtual reality system that allows users to climb an infinite virtual tower. Our set-up consists of an one-level scaffold and a lifter. A user climbs up the scaffold by real walking on a stairway while wearing a head-mounted display, and gets reset to the ground level by a lifter imperceptibly. By repeating this process, the user perceives an illusion of climbing an infinite number of levels. Our system achieves the illusion by (1) controlling the movement of the lifter to generate reverse and imperceptible motion, (2) guiding the user through the scaffold with delay mechanisms to reset the lifter in time, and (3) procedural generating overlapping structures to enlarge perceived height of each level. We built a working system and demonstrated it with a 15-min experience. With the working system, we conducted user studies to gain deeper insights into vertical motion simulation and vertical real walking in virtual reality.

Strength training improves overall health, well-being, physical appearance, and sports performance, with training programs specifying variables such as sets, repetitions, rest time, weight, and tempo. The repetitive nature of strength training, typically performed at fixed tempo, has made it challenging to develop entertaining exergames for common strength training exercises. We present StrengthGaming, which uses scaling and shuffling technique to provide tempo variations to strength training while preserving the training volume and training goals. It affords game designers more flexibility in designing strength training-based exergames. We developed a prototype game, inspired by FlappyBird, that uses a wearable orientation sensor to track the repetition tempo to control a flying character, using both fixed tempo design and dynamic tempo design. Results from our 24-person user study showed that dynamic tempo was significantly more entertaining than fixed tempo (p

We present Haptic-go-round, a surrounding platform that allows deploying props and devices to provide haptic feedbacks in any direction in virtual reality experiences. The key component of Haptic-go-round is a motorized turntable that rotates the correct haptic device to the right direction at the right time to match what users are about to touch. We implemented a working platform including plug-and-play prop cartridges and a software interface that allow experience designers to agilely add their haptic components and use the platform for their applications. We conducted technical experiments and two user studies on Haptic-go-round to evaluate its performance. We report the results and discuss our insights and limitations.

Strength training improves overall health, well-being, and sports performance. However, the training process is often repetitive, making the experiences boring and tiring after going through the long-term session. This paper proposes FitBird, which uses wearable sensors to map existing strength training motion to game designs to enhance entertainment level during exercising. We chose 1:1:1 as the time intervals proportion of three distinct phases during exercises repetition: 1) Eccentric: muscle lengthening, 2) Isometric: same muscle length, and 3) Concentric: muscle shortening, and integrated this tempo for the well-known game - FlappyBird as the training guidance. We evaluated the proof-of-concept prototype with 12-person study that participants conducted strength training while using our system. The results showed that FitBird significantly improve user's entertainment level during strength training and was preferred by most of the users.

There are several problems need to be solved in the process of the recognition of the point cloud target in the urban traffic scene: Low target recognition accuracy due to noise and low real-time performance when dealing with a large amount of data. Therefore, in order to improve the situation, a new method, SVM target recognition algorithm based on fast density clustering is proposed in this paper. The workflow of the algorithm includes: (1) Point cloud denoising. In this step, most noise points are removed, the adverse effect of noise on subsequent processing is avoided. (2) A fast density clustering algorithm, GLDBSCAN, is used for clustering and then the eigenvectors are extracted. (3) A SVM classifier is used to identify the point cloud target. Experimental results show that the algorithm is effective. The algorithm presented in this paper is more accurate and efficient than the previous point cloud recognition algorithms.

With the safe and stable operation of the new generation of power line carrier communication, it is of great significance to the rapid development of smart power grid. However, due to its own physical characteristics and the impact of the external environment, communication cables usually have some security risks, such as aging, damage, theft. In this paper, a new generation of power line carrier communication trusted access network is studied. In this paper, the current situation of the new generation of power line carrier trusted access and network requirements are analyzed, then the principle and characteristics of basic ant colony algorithm are briefly introduced, then the characteristics of power line carrier communication system network and network requirements are analyzed, the improved ant colony algorithm is applied to network optimization of the new generation of PLC communication system. The algorithm makes the power line carrier communication system have certain destruction resistance and recombination ability when the network state changes, it can guarantee the reliable operation of power network communication system.

Fluid Structure Interaction (FSI) is widely applied in aircraft aerodynamic and aeroelastic analysis. Iteration between the CFD and FEA will solve the aerodynamic force, flow field, structure stress and deformation under equilibrium state simultaneously. In aircraft product development, the CFD mesh and Finite element model normally do not match each other because the goal of CFD and FEA are different. To connect between unmatched interface, a pixelation method is developed to transfer the aerodynamic loads onto the finite element model correctly. The pixelation method is also easy to be implemented and parallelized.

Procedural generation in virtual reality (VR) has been used to adapt the virtual world to various indoor environments, fitting different geometries and interiors with virtual environments. However, such applications require that the physical environment be known or pre-scanned prior to use to then generate the corresponding virtual scene, thus restricting the virtual experience to a controlled space. In this paper, we present VRoamer, which enables users to walk unseen physical spaces for which VRoamer procedurally generates a virtual scene on-the-fly. Scaling to the size of office buildings, VRoamer extracts walkable areas and detects physical obstacles in real time, instantiates pre-authored virtual rooms if their sizes fit physically walkable areas or otherwise generates virtual corridors and doors that lead to undiscovered physical areas. The use of these virtual structures allows VRoamer to (1) temporarily block users' passage, thus slowing them down while increasing VRoamer's insight into newly discovered physical areas, (2) prevent users from seeing changes beyond the current virtual scene, and (3) obfuscate the appearance of physical environments. VRoamer animates virtual objects to reflect dynamically discovered changes of the physical environment, such as people walking by or obstacles that become apparent. In our proof-of-concept study, participants were able to walk long distances through a procedurally generated dungeon experience and reported high levels of immersion.

Short-term load prediction is important for demand side management at a distribution system. Accurate Load prediction for the distribution system operation is challenging due to the complicated load characteristics and numerous influence factors. In this paper a new hybrid load predicting strategy with input selection is introduced to improve the forecasting performance. The hybrid forecasting method contains a seasonal autoregressive integrated moving average function and a neural network (SARIMA-NN). The input selection aims to find the history days which has similar load curve as the forecasted day based on a heat index criteria (HI-SD), and the input variables are chosen by the factor affecting degree on different forecasted days. This novel strategy captures distinct load characteristics at different climate level, considering the effectively similarities between load days, choosing accurately input variables, and shows a great forecasting performance as demonstrated by a practical substation datasets.

We present a method of inspecting surface defects of ring magnets by using deep learning technology, and the inspection system developed utilizing this method has achieved much better accuracy and speed than human inspectors in actual production environment, while such accuracy and speed are essential for such systems. The proposed method can also be used for the surface defect inspection of many other industrial products and systems.

In fluid-structure interaction simulations using a partitioned approach, especially aeroelastic analysis, each physics component solves on its own mesh, and the interface between these meshes are in general non-matching. Force and displacement must be transferred from one mesh to another. Generally speaking, two classes of methods have been developed and applied in engineering: point wise interpolation and mapping method. For practical problems, point wise interpolation is not good enough in conversation and mapping method requires detailed meshes to describe surfaces of both fluid side and structure side. This paper presents a flexible, conservative and robust method which only requires surface mesh on fluid side. The merits of new method in terms of conversation properties were discussed. Also, the numerical results of practical problems are demonstrated in this paper.

Although virtual reality hardware is now widely available, the uptake of real walking is hindered by the fact that it requires often impractically large amounts of physical space. To address this, we present VirtualSpace, a novel system that allows overloading multiple users immersed in different VR experiences into the same physical space. VirtualSpace accomplishes this by containing each user in a subset of the physical space at all times, which we call tiles; app-invoked maneuvers then shuffle tiles and users across the entire physical space. This allows apps to move their users to where their narrative requires them to be while hiding from users that they are confined to a tile. We show how this enables VirtualSpace to pack four users into 16m2. In our study we found that VirtualSpace allowed participants to use more space and to feel less confined than in a control condition with static, pre-allocated space.

We present a system that complements virtual reality experiences with passive props, yet still allows modifying the virtual world at runtime. The main contribution of our system is that it does not require any actuators; instead, our system employs the user to reconfigure and actuate otherwise passive props. We demonstrate a foldable prop that users reconfigure to represent a suitcase, a fuse cabinet, a railing, and a seat. A second prop, suspended from a long pendulum, not only stands in for inanimate objects, but also for objects that move and demonstrate proactive behavior, such as a group of flying droids that physically attack the user. Our approach conveys a sense of a living, animate world, when in reality the user is the only animate entity present in the system, complemented with only one or two physical props. In our study, participants rated their experience as more enjoyable and realistic than a corresponding no-haptics condition.

Human actuation is the idea of using people to provide large-scale force feedback to users. The Haptic Turk system, for example, used four human actuators to lift and push a virtual reality user; TurkDeck used ten human actuators to place and animate props for a single user. While the experience of human actuators was decent, it was still inferior to the experience these people could have had, had they participated as a user. In this paper, we address this issue by making everyone a user. We introduce mutual human actuation, a version of human actuation that works without dedicated human actuators. The key idea is to run pairs of users at the same time and have them provide human actuation to each other. Our system, Mutual Turk, achieves this by (1) offering shared props through which users can exchange forces while obscuring the fact that there is a human on the other side, and (2) synchronizing the two users' timelines such that their way of manipulating the shared props is consistent across both virtual worlds. We demonstrate mutual human actuation with an example experience in which users pilot kites though storms, tug fish out of ponds, are pummeled by hail, battle monsters, hop across chasms, push loaded carts, and ride in moving vehicles.

We explore how to add haptics to walls and other heavy objects in virtual reality. When a user tries to push such an object, our system actuates the user's shoulder, arm, and wrist muscles by means of electrical muscle stimulation, creating a counter force that pulls the user's arm backwards. Our device accomplishes this in a wearable form factor. In our first user study, participants wearing a head-mounted display interacted with objects provided with different types of EMS effects. The repulsion design (visualized as an electrical field) and the soft design (visualized as a magnetic field) received high scores on "prevented me from passing through" as well as "realistic". In a second study, we demonstrate the effectiveness of our approach by letting participants explore a virtual world in which all objects provide haptic EMS effects, including walls, gates, sliders, boxes, and projectiles.

We propose a class of passive haptics that we call Sparse Haptic Proxy: a set of geometric primitives that simulate touch feedback in elaborate virtual reality scenes. Unlike previous passive haptics that replicate the virtual environment in physical space, a Sparse Haptic Proxy simulates a scene's detailed geometry by redirecting the user's hand to a matching primitive of the proxy. To bridge the divergence of the scene from the proxy, we augment an existing Haptic Retargeting technique with an on-the-fly target remapping: We predict users' intentions during interaction in the virtual space by analyzing their gaze and hand motions, and consequently redirect their hand to a matching part of the proxy. We conducted three user studies on haptic retargeting technique and implemented a system from three main results: 1) The maximum angle participants found acceptable for retargeting their hand is 40°, with an average rating of 4.6 out of 5. 2) Tracking participants' eye gaze reliably predicts their touch intentions (97.5%), even while simultaneously manipulating the user's hand-eye coordination for retargeting. 3) Participants preferred minimized retargeting distances over better-matching surfaces of our Sparse Haptic Proxy when receiving haptic feedback for single-finger touch input. We demonstrate our system with two virtual scenes: a flight cockpit and a room quest game. While their scene geometries differ substantially, both use the same sparse haptic proxy to provide haptic feedback to the user during task completion.

The lattice Boltzmann method has become an attractive and promising approach in computational fluid dynamics. In this paper, the D3Q19 multi-relaxation-time lattice Boltzmann method is employed to simulate complex fluid flow and its parallel algorithm is presented including Cartesian grid generation, domain decomposition method, and data exchange strategy on clusters. Considering load balancing on large scale cluster, details of domain decomposition method are presented. The numerical results show that the presented algorithm have considerable scalability on 2048 cores and the efficiency can achieve 92.01%.

TurkDeck is an immersive virtual reality system that reproduces not only what users see and hear, but also what users feel. TurkDeck produces the haptic sensation using props, i.e., when users touch or manipulate an object in the virtual world, they simultaneously also touch or manipulate a corresponding object in the physical world. Unlike previous work on prop-based virtual reality, however, TurkDeck allows creating arbitrarily large virtual worlds in finite space and using a finite set of physical props. The key idea behind TurkDeck is that it creates these physical representations on the fly by making a group of human workers present and operate the props only when and where the user can actually reach them. TurkDeck manages these so-called "human actuators" by displaying visual instructions that tell the human actuators when and where to place props and how to actuate them. We demonstrate TurkDeck at the example of an immersive 300m2 experience in 25m2 physical space. We show how to simulate a wide range of physical objects and effects, including walls, doors, ledges, steps, beams, switches, stompers, portals, zip lines, and wind. In a user study, participants rated the realism/immersion of TurkDeck higher than a traditional prop-less baseline condition (4.9 vs. 3.6 on 7 item Likert).

We present "Level-Ups", computer-controlled stilts that allow virtual reality users to experience walking up and down steps. Each Level-Up unit is a self-contained device worn like a boot. Its main functional element is a vertical actuation mechanism mounted to the bottom of the boot that extends vertically. Unlike traditional solutions that are integrated with locomotion devices, Level-Ups allow users to walk around freely ("real-walking"). We present Level-Ups in a demo environment based on a head-mounted display, optical motion capture, and integrated with two different game engines. In a user study, participants rated the realism of stepping onto objects 6.0 out of 7.0 when wearing Level-Ups compared to 3.5 without.

Motion platforms are used to increase the realism of virtual interaction. Unfortunately, their size and weight is proportional to the size of what they actuate. We present haptic turk, a different approach to motion platforms that is light and mobile. The key idea is to replace motors and mechanical components with humans. All haptic turk setups consist of a player who is supported by one or more turkers. The player enjoys an interactive experience, such as a flight simulation. The motion in the player's experience is generated by the turkers who manually lift, tilt, and push the player's limbs or torso. To get the timing and force right, timed motion instructions in a format familiar from rhythm games are displayed on turkers' mobile devices, which they attach to the player's body. We demonstrate a range of installations based on mobile phones, projectors, and head-mounted displays. In our user study, participants rated not only the experience as player as enjoyable (6.1/7), but also the experience as a turker (4.4/7). The approach of leveraging humans allows us to deploy our approach anytime anywhere, as we demonstrate by experimentally deploying at an art festival in the Nevada desert.

Motion platforms are used to increase the realism of virtual interaction. Unfortunately, their size and weight is proportional to what they actuate. We present haptic turk, a different approach to motion platforms that is light and mobile. The key idea is to replace motors and mechanical components with humans. All haptic turk setups consist of a player who is supported by one or more “turkers”. The player enjoys an interactive expe-rience, such as a flight simulation. The motion in the player's experience is generated by the turkers who manually lift, tilt, and push the player's limbs or torso. To get the timing and force right, timed motion instructions in a format familiar from rhythm games are dis-played on turkers' mobile devices, which they attach to the player's body. We also present an immersive set-up based on a head-mounted display.

Multitouch tablets, such as iPad and Android tablets, support virtual keyboards for text entry. Our 64-user study shows that 98% of the users preferred different keyboard layouts and positions depending on how they were holding these devices. However, current tablets either do not allow keyboard adjustment or require users to manually adjust the keyboards. We present iGrasp, which automatically adapts the layout and position of virtual keyboards based on how and where users are grasping the devices without requiring explicit user input. Our prototype uses 46 capacitive sensors positioned along the sides of an iPad to sense users' grasps, and supports two types of grasp-based automatic adaptation: layout switching and continuous positioning. Our two 18-user studies show that participants were able to begin typing 42% earlier using iGrasp's adaptive keyboard compared to the manually adjustable keyboard. Participants also rated iGrasp much easier to use than the manually adjustable keyboard (4.2 vs 2.9 on five-point Likert scale.)

Automatic screen rotation improves viewing experience and usability of mobile devices, but current gravity-based approaches do not support postures such as lying on one side, and manual rotation switches require explicit user input. iRotateGrasp automatically rotates screens of mobile devices to match users' viewing orientations based on how users are grasping the devices. Our insight is that users' grasps are consistent for each orientation, but significantly differ between different orientations. Our prototype used a total of 44 capacitive sensors along the four sides and the back of an iPod Touch, and uses support vector machine (SVM) to recognize grasps at 25Hz. We collected 6-users' usage under 108 different combinations of posture, orienta-tion, touchscreen operation, and left/right/both hands. Our offline analysis showed that our grasp-based approach is promising, with 80.9% accuracy when training and testing on different users, and up to 96.7% if users are willing to train the system. Our user study (N=16) showed that iRo-tateGrasp had an accuracy of 78.8% and was 31.3% more accurate than gravity-based rotation.

Automatic screen rotation improves viewing experience and usability of mobile devices, but current gravity-based approaches do not support postures such as lying on one side, and manual rotation switches require explicit user input. iRotate Grasp automatically rotates screens of mobile devices to match users' viewing orientations based on how users are grasping the devices. Our insight is that users' grasps are consistent for each orientation, but significantly differ between different orientations. Our prototype embeds a total of 32 light sensors along the four sides and the back of an iPod Touch, and uses support vector machine (SVM) to recognize grasps at 25Hz. We collected 6-users' usage under 54 different conditions: 1) grasping the device using left, right, and both hands, 2) scrolling, zooming and typing, 3) in portrait, landscape-left, and landscape-right orientations, and while 4) sitting and lying down on one side. Results show that our grasp-based approach is promising, and our iRotate Grasp prototype could correctly rotate the screen 90.5% of the time when training and testing on different users.

We present iRotate, an approach to automatically rotate screens on mobile devices to match users' face orientation. Current approaches to automatic screen rotation are based on gravity and device orientation. Our survey of 513 users shows that 42% currently experience auto-rotation that leads to incorrect viewing orientation several times a week or more, and 24% find the problem to be very serious to extremely serious. iRotate augments gravity-based approach, and uses front cameras on mobile devices to detect users' faces and rotates screens accordingly. It requires no explicit user input and supports different user postures and device orientations. We have implemented a iRotate that works in real-time on iPhone and iPad, and we assess the accuracy and limitations of iRotate through a 20- participant feasibility study.

We present TUIC, a technology that enables tangible interaction on capacitive multi-touch devices, such as iPad, iPhone, and 3M's multi-touch displays, without requiring any hardware modifications. TUIC simulates finger touches on capacitive displays using passive materials and active modulation circuits embedded inside tangible objects, and can be used with multi-touch gestures simultaneously. TUIC consists of three approaches to sense and track objects: spatial, frequency, and hybrid (spatial plus frequency). The spatial approach, also known as 2D markers, uses geometric, multi-point touch patterns to encode object IDs. Spatial tags are straightforward to construct and are easily tracked when moved, but require sufficient spacing between the multiple touch points. The frequency approach uses modulation circuits to generate high-frequency touches to encode object IDs in the time domain. It requires fewer touch points and allows smaller tags to be built. The hybrid approach combines both spatial and frequency tags to construct small tags that can be reliably tracked when moved and rotated. We show three applications demonstrating the above approaches on iPads and 3M's multi-touch displays.

We propose two approaches to sense tangible objects on capacitive touch screens, which are used in off-the-shelf multi-touch devices such as Apple iPad, iPhone, and 3M's multi-touch displays. We seek for the approaches that do not require modifications to the panels: spatial tag and frequency tag. Spatial tag is similar to fiducial tag used by tangible tabletop surface interaction, and uses multi-point, geometric patterns to encode object IDs. Frequency tag simulates high-frequency touches in the time domain to encode object IDs, using modulation circuits embedded inside tangible objects to simulate high-speed touches in varying frequency. We will show several demo applications. The first combines simultaneous tangible + touch input system. This explores how tangible inputs (e.g., pen, easer, etc.) and some simple gestures work together on capacitive touch panels.

The output of VCLC sublayer was taken as the input of the VCA sublayer on CCSDS AOS, whose multiplexing efficiency and formed-time directly affect the performance of the virtual channel and whole system. Based on Poisson distribution, the research on multiplexing efficiency was transformed into the occurred probability of packets arriving. While establishing the probability and statistics model of packets channel multiplexing, a new virtual channel scheduling model with weighted slots and the optimized throughput was proposed, which combined MPDU formed-time of VCLC sublayer with scheduling time of VCA sublayer. Simulation results showed that the new cross-layer model can increase channel throughput and reduced transfer delay.

The AOS packet service organization is presented firstly in this paper. Based on it, the AOS packet service throughput is analyzed. Then the relations between the frame length of AOS space data link protocol sublayer, bit error rate (ber) of physical layer and the AOS throughput are discussed and the optimal frame length which gains the maximum throughput under a certain ber is obtained. Consequently, a frame length adaptive scheme is proposed to control the frame length for the maximum throughput according to the different channel state information (CSI). Simulation results show that compared with fixed length frame transmission, the proposed scheme can improve the AOS throughput performance availably.

In this paper, the throughput of AOS protocol packet service under binary memoryless random error channel is studied. A throughput formula is given, and the impact of transfer frame length on throughput is also discussed. It is shown that an optimal AOS transfer frame length which maximizes the throughput under a certain bit error rate (BER) does exist, and its uniqueness is also verified. Finally, a channel adaptive strategy based on the BER values is proposed to control the frame length to obtain the maximum throughput. Simulation results show that compared with fixed length frame transmission, the proposed strategy can improve the throughput greatly.

Recently, the reconfiguration technology has been applied to the network control so that the ability of recovery, self-healing and survivability in the failure and unsafe environment can be supplied. However, it is not adequate for mobile ad hoc network because of a kind of active and autonomic behavior ignored in the normal network operation. Therefore, a new reconfiguration based on the 3-phase policy is proposed for supporting the relative stabilization, reliability and adjustment in the network clustering. Besides, the clustering algorithms for mobile ad hoc network are evaluated on the opinion of reconfiguration planning.

When a quantum cryptographic system operates in the presence of background noise, security of the key can be recovered by a procedure called key distillation. A key-distillation scheme effective against so-called individual (bitwise-independent) eavesdropping attacks involves sacrifice of some of the data through privacy amplification. We derive the amount of data sacrifice sufficient to defend against individual eavesdropping attacks in both BB84 and B92 protocols and show in what sense the communication becomes secure as a result. We also compare the secrecy capacity of various quantum cryptosystems, taking into account data sacrifice during key distillation, and conclude that the BB84 protocol may offer better performance characteristics than the B92.