diff --git a/src/KSP-tools/calculator_dv.py b/src/KSP-tools/calculator_dv.py
index 14d000d..5a31b34 100644
--- a/src/KSP-tools/calculator_dv.py
+++ b/src/KSP-tools/calculator_dv.py
@@ -113,6 +113,9 @@ if __name__ == '__main__':
     # x = cal_fuel_burned(333, 80, 610) + cal_fuel_burned(350, 823.2, 148)
     # x = cal_dv(338.2, 55000, 70000)
     # xx = cal_fuel_burned(21000, 400, 1)
+
+    print(cal_dv(298.7, 12.48, 13.52))
+
     x = cal_kinetic_energy(350, 2450, 1, 1)
     # x = cal_kinetic_energy(314.3, 931, 1, 1)
     y = cal_kinetic_energy(21000, 800, 1, 1)
diff --git a/src/KSP-tools/load_common_resources.py b/src/KSP-tools/load_common_resources.py
index a54841b..d77476a 100644
--- a/src/KSP-tools/load_common_resources.py
+++ b/src/KSP-tools/load_common_resources.py
@@ -12,6 +12,8 @@ def cal_fuel_density(fuel_type):
         fuel_density = lqdmethane['density'] * 0.4137 + lox['density'] * 0.5863
     elif fuel_type == 'hydrolox':
         fuel_density = lh2['density'] * 0.7276 + lox['density'] * 0.2724
+    elif fuel_type == 'MMH/NTO':
+        fuel_density = common_resources_dict['MMH']['density'] * 0.499 + common_resources_dict['NTO']['density'] * 0.501
     else:
         raise TypeError
     return fuel_density
@@ -87,5 +89,6 @@ if __name__ == '__main__':
     print(cal_tank_volume(339000, 'kerolox'))
     print(cal_fuel_mass({'Kerosene': 48345.13, 'LqdOxygen': 90298.77}))
     print(cal_fuel_mass_based_on_tank_volume('kerolox', 108000))
-    print(cal_fuel_mass({'LqdHydrogen':54802.1756419623, 'LqdOxygen':20516.9222581005}))
+    print(cal_fuel_mass({'LqdHydrogen': 54802.1756419623, 'LqdOxygen': 20516.9222581005}))
+    print(cal_fuel_density('MMH/NTO'), cal_fuel_density('methalox'))
     print('done')
diff --git a/src/tools/auto_safe.py b/src/tools/auto_safe.py
new file mode 100644
index 0000000..e9ea845
--- /dev/null
+++ b/src/tools/auto_safe.py
@@ -0,0 +1,89 @@
+import time
+from ctypes import *
+from tcping import Ping
+
+
+def ping_ip(ip_address, request_nums):
+    """
+    ping ip
+    :param ip_address:
+    :param request_nums: 请求次数
+    :return: 丢包率loss和统计结果res
+    """
+    ping = Ping(ip_address, 22, 3)
+    ping.ping(request_nums)
+    res = ping.result.table
+    ret = ping.result.raw
+    return_list = list(ret.split('\n'))
+    loss = return_list[2].split(',')[3].split(' ')[1]  # 获取丢包率
+    return loss, res
+
+
+def ping_process(host):
+    # 调用ping_ip方法得到丢包率
+    loss, res = ping_ip(host, 3)
+    if float(loss.strip('%')) / 100 <= 0.1:  # 0.1为自定义丢包率阈值，可修改
+        print("ping 不通")
+    else:
+        print("ping 通")
+
+
+def shut_screen_and_lock():
+    windll.user32.PostMessageW(0xffff, 0x0112, 0xF170, 2)
+    shell32 = windll.LoadLibrary("shell32.dll")
+    shell32.ShellExecuteW(None, 'open', 'rundll32.exe', 'USER32,LockWorkStation', '', 5)
+
+
+def is_locked():
+    # 导入 user32.dll
+    user32 = windll.User32
+
+    # 检查锁定状态, 如果结果为0，则系统处于锁定状态，否则系统处于解锁状态
+    result = user32.GetForegroundWindow()
+    return True if result == 0 else False
+
+
+class AutoSafe:
+    """
+
+    """
+
+    def __init__(self, cool_down_time: int, delay_time: int, target_server: str):
+        self.cool_down_time = cool_down_time
+        self.delay_time = delay_time
+        self.target_server = target_server
+        self.start_monitor = True
+
+    def check_connection(self) -> bool:
+        loss, res = ping_ip(self.target_server, 5)
+        if float(loss.strip('%')) / 100 <= 0.1:
+            return False
+        else:
+            return True
+
+    def run(self):
+        print("Starting AutoSafe")
+        while self.start_monitor:
+            time.sleep(20)
+            if is_locked() or self.check_connection():
+                continue
+            else:
+                self.safe()
+
+    def safe(self):
+        print('Safe armed at ' + time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
+        time.sleep(self.delay_time)
+        if not is_locked() and not self.check_connection():
+            print('Safe activated at ' + time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
+            shut_screen_and_lock()
+            time.sleep(self.cool_down_time)
+        return
+
+
+if __name__ == '__main__':
+    auto_safe = AutoSafe(cool_down_time=3600 * 8, delay_time=60, target_server='192.168.195.194')
+    auto_safe.run()
+    # ping('192.168.195.194')
+    # while 1:
+    #     print(is_locked(), time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
+    #     time.sleep(1)